Java 21: Virtual Threads

Java 21 introduces lightweight concurrency with Virtual Threads.

Virtual threads are a different approach to asynchronous programming. Instead of having to rewrite everything using async/await keywords. Java will take care of everything.

Discover the changes introduced with JDK 21 and learn how Virtual Threads behaves with code examples demonstrating I/O Bound Tasks, CPU Bound Tasks, and Cooperative CPU Bound Tasks. Learn how the synchronized keyword and locks work in the context of Virtual Threads.

https://youtu.be/JWZxyrHBppA

Transcript

1. JDK 21 LTS Virtual Threads a Different Approach to Async/Await
2. Aims to Bring easy-to-use, high-throughput, lightweight concurrency and new programming models on the Java platform. JDK 21 LTS
3. JDK 21: Virtual Threads A different Approach to asynchronous programming C#, Python, Javascript, C++, Rust async/await Introduced New Keywords requiring a significant rewrite to take advantage of this model choose code compatibility minimizing the impact on existing code to benefit from this model
4. JDK 21: Threads Platform Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. // create a platform thread, and use .start() to start it. Thread thread = new Thread(Runnable, "thread-name") thread.start(); // create a platform thread, and use .start() to start it. Thread thread = Thread.ofPlatform().name("thread-name").unstarted(Runnable); thread.start(); // create a platform thread and start it. No need to call .start() Thread thread = Thread.ofPlatform().name("thread-name").start(Runnable);
5. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Platform Threads & Executor Services
6. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } } Platform Threads & Executor Services
7. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
8. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
9. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
10. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
11. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
12. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
13. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
14. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
15. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
16. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
17. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
18. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
19. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
20. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
21. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
22. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
23. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
24. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
25. JDK 21: Threads Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue Platform Threads & Executor Services try (ExecutorService executor = Executors.newFixedThreadPool(4)) { for (int i = 0; i < 100; ++i) { executor.submit(() -> myTask()); } }
26. JDK 21: Executor Services Slow Tasks & Completable Future Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue
27. JDK 21: Executor Services Slow Tasks & Completable Future Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue
28. JDK 21: Executor Services Slow Tasks & Completable Future Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue
29. JDK 21: Executor Services Slow Tasks & Completable Future Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue
30. JDK 21: Executor Services Slow Tasks & Completable Future Kernel space User space (JVM) Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs Task Queue
31. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs In most backend services Slow Tasks are I/O Bound Tasks
32. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling
33. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling My Task Not being blocked
34. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
35. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
36. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
37. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
38. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
39. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
40. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
41. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
42. JDK 21: Executor Services Slow Tasks & Completable Future Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Platform Threads are not cheap - startup time: ~1ms - memory consumption: 2MB of stack - context switch: ~100μs System.out.println("Active Threads " + Thread.activeCount()); for (int i = 0; i < 128; ++i) { httpClient.sendAsync(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); System.out.println("Active Threads " + Thread.activeCount()); } CompletableFuture and the Async feeling All the threads created by .sendAsync() Waiting for I/O My Task Not being blocked
43. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) // create a virtual thread and start it. Thread thread = Thread.startVirtualThread(Runnable); // create a virtual thread and start it. Thread thread = Thread.ofVirtual().name(“thread-name").start(Runnable); // create a virtual thread, and use .start() to start it. Thread thread = Thread.ofVirtual().name("thread-name").unstarted(Runnable); thread.start(); Virtual Threads JVM
44. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads Eliminates the overhead of I/O Bound Tasks
45. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) Virtual Threads JVM
46. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) Virtual Threads JVM Use them for I/O Bound Tasks
47. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) Virtual Threads JVM Use them for I/O Bound Tasks Spends most of the time using CPU Spends most of the time waiting for I/O Longer CPU bursts Shorter CPU bursts CPU Bound I/O Bound
48. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) Virtual Threads JVM Almost no changes to the code required! Java did all of the work underneath Rewriting the I/O & Blocking Operations To Cooperate with the Virtual Threads Scheduler
49. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { executor.submit(() -> myTask()); } Virtual Threads JVM
50. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads User space (JVM) // create a virtual thread and start it. Thread thread = Thread.startVirtualThread(Runnable); // create a virtual thread and start it. Thread thread = Thread.ofVirtual().name(“thread-name").start(Runnable); // create a virtual thread, and use .start() to start it. Thread thread = Thread.ofVirtual().name("thread-name").unstarted(Runnable); thread.start(); Virtual Threads JVM
51. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads // create a platform thread and start it. No need to call .start() Thread thread = Thread.ofPlatform().name(“my-thread-name”).start(Runnable); // create a virtual thread and start it. Thread thread = Thread.ofVirtual().name(“my-thread-name”).start(Runnable); boolean isVirtual = thread.isVirtual();
52. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads // create a platform thread and start it. No need to call .start() Thread thread = Thread.ofPlatform().name(“my-thread-name”).start(Runnable); // create a virtual thread and start it. Thread thread = Thread.ofVirtual().name(“my-thread-name”).start(Runnable); boolean isVirtual = thread.isVirtual(); Thread[#29,my-thread-name,5,main] VirtualThread[#30,my-thread-name]/runnable@ForkJoinPool-1-worker-1 jstack or Thread.currentThread() shows
53. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. JDK 21: Threads Virtual Threads // create a platform thread and start it. No need to call .start() Thread thread = Thread.ofPlatform().name(“my-thread-name”).start(Runnable); // create a virtual thread and start it. Thread thread = Thread.ofVirtual().name(“my-thread-name”).start(Runnable); boolean isVirtual = thread.isVirtual(); Thread[#29,my-thread-name,5,main] VirtualThread[#30,my-thread-name]/runnable@ForkJoinPool-1-worker-1 jstack or Thread.currentThread() shows
54. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Kernel space User space (JVM) Virtual Threads Carrier Threads
55. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Kernel space User space (JVM) Virtual Threads Carrier Threads ForkJoinPool with FIFO order
56. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Kernel space User space (JVM) Virtual Threads Carrier Threads ForkJoinPool with FIFO order -Djdk.virtualThreadScheduler.parallelism=16 -Djdk.virtualThreadScheduler.maxPoolSize=256 The number of platform threads available for scheduling virtual threads. It defaults to the number of available processors. The maximum number of platform threads available to the scheduler. It defaults to 256.
57. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread
58. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ...
59. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ...
60. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ...
61. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ...
62. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ...
63. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks
64. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap
65. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
66. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
67. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
68. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
69. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
70. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
71. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
72. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
73. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
74. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
75. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
76. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
77. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
78. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
79. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
80. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
81. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
82. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap Task State
83. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap
84. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads Virtual Threads Carrier Thread // some cpu bound code long result = 0; for (int i = 0; i < 100; ++i) { result += i * 3; } // some blocking (I/O bound) code HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create(“https://myservice/test”)) .GET() .build(), BodyHandlers.discarding()); // more cpu bound code if (resp.statusCode() != 200) { ... Waiting Tasks JVM Heap
85. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads public void myTask() { // each execution step may run on a different Carrier Thraed cpuBoundOperations(); // run on CarrierThread-5 ioBoundOperations(); // goes to "waiting" cpuBoundOperations(); // run on CarrierThread-3 ioBoundOperations(); // goes to "waiting" cpuBoundOperations(); // run on CarrierThread-3 // ... }
86. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads public void myTask() { // each execution step may run on a different Carrier Thraed cpuBoundOperations(); // run on CarrierThread-5 ioBoundOperations(); // goes to "waiting" cpuBoundOperations(); // run on CarrierThread-3 ioBoundOperations(); // goes to "waiting" cpuBoundOperations(); // run on CarrierThread-3 // ... } ThreadLocals are available for compatibility but not really useful. Do not pool VirtualThreads!
87. Virtual Threads User-mode threads scheduled by the Java Runtime rather than the operating system Platform Threads Typically mapped 1:1 to kernel threads scheduled by the operating system. Carrier Threads Set of Platform threads responsible for running virtual threads. JDK 21: Threads Platform, Virtual & Carrier Threads public void myTask() { // each execution step may run on a different Carrier Thraed cpuBoundOperations(); // run on CarrierThread-5 ioBoundOperations(); // goes to "waiting" cpuBoundOperations(); // run on CarrierThread-3 ioBoundOperations(); // goes to "waiting" cpuBoundOperations(); // run on CarrierThread-3 // ... } ThreadLocals are available for compatibility but not really useful. Do not pool VirtualThreads! ScopedValue<MyObject> SHARED_OBJECT = ScopedValue.newInstance(); ScopedValues, the better alternative to ThreadLocal are only available as preview (in JDK 21)
88. Code Examples Let's see how Virtual Threads behaves
89. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } }
90. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } We are using the synchronous .send() No callbacks, futures & co
91. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } }
92. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
93. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
94. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
95. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
96. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
97. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
98. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
99. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
100. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
101. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
102. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
103. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
104. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
105. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
106. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
107. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
108. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
109. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
110. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
111. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
112. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
113. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
114. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
115. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
116. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
117. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
118. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
119. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
120. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
121. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
122. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
123. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
124. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
125. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
126. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
127. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
128. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
129. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
130. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
131. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
132. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
133. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
134. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
135. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
136. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
137. JDK 21: Virtual Threads I/O Bound Tasks private static long ioBoundTask() { try { // calls a service that waits 5sec before responding… final HttpResponse<Void> resp = httpClient.send(HttpRequest.newBuilder() .uri(URI.create("https://hub.dummyapis.com/delay?seconds=5")) .GET() .build(), BodyHandlers.discarding()); // ... return resp.statusCode(); } catch (final Exception e) { // ignore... System.err.println("http req failed: " + e.getMessage()); return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks
138. JDK 21: Virtual Threads I/O Bound Tasks private static int sleepBoundTask() { try { // sleep() acts as an I/O operation, allowing the task unmount Thread.sleep(5_000); return 0; } catch (final InterruptedException e) { // ignore... return -1; } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); final Thread[] threads = new Thread[10]; for (int i = 0; i < threads.length; ++i) { final int taskId = i; threads[i] = Thread.ofVirtual().start(() -> { sleepBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } for (final Thread thread : threads) { thread.join(); final boolean isVirtual = thread.isVirtual(); }
139. JDK 21: Virtual Threads CPU Bound Tasks Virtual Threads are made for I/O Bound Tasks Let’s see how they will behave with CPU Bound Tasks
140. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } There are no blocking points in the code To Unmount the Virtual Thread
141. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads
142. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads
143. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s
144. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s
145. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s
146. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s
147. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s
148. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s
149. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s 5. Completed in 15s 6. Completed in 15s
150. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s 5. Completed in 15s 6. Completed in 15s
151. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s 5. Completed in 15s 6. Completed in 15s 7. Completed in 20s 8. Completed in 20s
152. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s 5. Completed in 15s 6. Completed in 15s 7. Completed in 20s 8. Completed in 20s
153. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Threads 1. Completed in 5s 2. Completed in 5s 3. Completed in 10s 4. Completed in 10s 5. Completed in 15s 6. Completed in 15s 7. Completed in 20s 8. Completed in 20s 9. Completed in 25s 10.Completed in 25s
154. JDK 21: Virtual Threads CPU Bound Tasks private static long cpuBoundTask() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { count++; } return count; } // Run with -Djdk.virtualThreadScheduler.parallelism=2 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTask(); long elapsedNs = System.nanoTime() - startTime; }); } } For CPU bound Tasks Virtual Threads gives no advantage over traditional (Platform Thread based) ExecutorServices And I/O Bound Tasks Have to wait CPU Bound Tasks to Finish
155. Virtual Threads Carrier Threads CPU Bound Tasks Platform Threads Send CPU and I/O bound tasks to dedicated executors ThreadPoolExecutor VirtualThraedPerTaskExecutor JDK 21: Virtual Threads
156. JDK 21: Virtual Threads Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; } CPU Bound Tasks can cooperate Using the yield() method
157. JDK 21: Virtual Threads Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } Carrier Thread Waiting Tasks private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
158. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
159. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
160. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
161. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
162. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
163. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
164. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
165. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
166. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
167. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
168. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
169. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
170. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
171. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
172. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
173. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
174. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
175. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
176. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
177. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
178. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
179. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
180. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
181. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
182. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
183. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
184. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
185. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
186. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
187. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
188. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
189. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
190. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
191. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
192. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
193. JDK 21: Virtual Threads Carrier Thread Waiting Tasks Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; }
194. JDK 21: Virtual Threads Cooperative CPU Bound Tasks // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { cpuBoundTaskWithYield(); long elapsedNs = System.nanoTime() - startTime; }); } } private static long cpuBoundTaskWithYield() { final long startTime = System.nanoTime(); long count = 0; while ((System.nanoTime() - startTime) < TimeUnit.SECONDS.toNanos(5)) { if (count++ % 100 == 0) { Thread.yield(); } } return count; } Slower than running the task alone (Since the CPU is shared) But it’s the same behaviour of running multiple platform Threads
195. JDK 21: Virtual Threads The synchronized keyword private final static Object[] lock = new Object[4]; static { for (int i = 0; i < lock.length; ++i) { lock[i] = new Object(); } } private static long ioSynchronizedTask(final int taskId) { synchronized (lock[taskId % lock.length]) { return ioBoundTask(); } } synchronized will block the carrier thread
196. JDK 21: Virtual Threads The synchronized keyword private final static Object[] lock = new Object[4]; static { for (int i = 0; i < lock.length; ++i) { lock[i] = new Object(); } } private static long ioSynchronizedTask(final int taskId) { synchronized (lock[taskId % lock.length]) { return ioBoundTask(); } } Multiple synchronized Object Will not help If you are lucky You’ll get the CPU Bound Task Behaviour Even on I/O Operations
197. JDK 21: Virtual Threads The synchronized keyword private final static Object[] lock = new Object[4]; static { for (int i = 0; i < lock.length; ++i) { lock[i] = new Object(); } } private static long ioSynchronizedTask(final int taskId) { synchronized (lock[taskId % lock.length]) { return ioBoundTask(); } } Remove the use of Synchronized
198. JDK 21: Virtual Threads Locks: Reentrant Lock, Semaphores, … private static final ReentrantLock[] rlock = new ReentrantLock[4]; static { for (int i = 0; i < rlock.length; ++i) { rlock[i] = new ReentrantLock(); } } private static long ioLockedTask(final int taskId) { final ReentrantLock lock = rlock[taskId % rlock.length]; lock.lock(); try { return ioBoundTask(); // http.send(), sleep(), ... } finally { lock.unlock(); } } // Run with -Djdk.virtualThreadScheduler.parallelism=1 final long startTime = System.nanoTime(); try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) { for (int i = 0; i < 10; ++i) { final int taskId = i; executor.submit(() -> { ioLockedTask(); long elapsedNs = System.nanoTime() - startTime; }); } } 4 Tasks will run concurrently Locks are a blocking operation Releasing the Virtual Thread from the Carrier
199. JDK 21 Virtual Threads Do not go and replace all your ExecutorServices with Virtual Threads! CPU Bound Tasks will not benefit from it Virtual Threads are made for I/O bound Tasks Spends most of the time using CPU Spends most of the time waiting for I/O Longer CPU bursts Shorter CPU bursts CPU Bound I/O Bound
200. JDK 21 Virtual Threads Do not go and replace all your ExecutorServices with Virtual Threads! CPU Bound Tasks will not benefit from it Virtual Threads are made for I/O bound Tasks Spends most of the time using CPU Spends most of the time waiting for I/O Longer CPU bursts Shorter CPU bursts CPU Bound I/O Bound Virtual Threads A Service or a Database
201. JDK 21 Virtual Threads Do not go and replace all your ExecutorServices with Virtual Threads! CPU Bound Tasks will not benefit from it Virtual Threads are made for I/O bound Tasks Spends most of the time using CPU Spends most of the time waiting for I/O Longer CPU bursts Shorter CPU bursts CPU Bound I/O Bound Virtual Threads A Service or a Database Can your Database, Service, Disk, … handle the extra concurrency? (Probably not) If you are using Virtual Threads You should limit the access To a Resource Using a Semaphore (or similar)