Vaclav Pech on GPars

Transcript

1. GPars Promises to keep Václav Pech
2. About me ['Passionate programmer', 'Concurrency enthusiast', 'GPars lead', 'Developer/technology evangelist @ JetBrains' ].eachParallel {say it} http://www.jroller.com/vaclav http://twitter.com/vaclav_pech
3. We're all parallel now Use them or leave them!
5. # of cores
6. # of cores Today Soon
7. Dealing with threads sucks! public class Counter { private static long count = 0; public Counter() { count++; } }
8. Dealing with threads sucks! public class Counter { private static long count = 0; public Counter() { synchronized (this) { count++; } } }
9. Dealing with threads sucks! public class Counter { private static long count = 0; public Counter() { synchronized (this.getClass()) { count++; } } }
10. Dealing with threads sucks! public class ClickCounter implements ActionListener { public ClickCounter(JButton button) { button.addActionListener(this); } public void actionPerformed(final ActionEvent e) { ... } }
11. images.eachParallel {it.process()} documents.sumParallel() candidates.maxParallel {it.salary}.marry() Parallel Collections
12. Parallel Collections progLanguages.parallel.filter {it.concurrent} .max {it.javaInteroperability} .map {it.logo} ==
13. Fork/Join  Solve hierarchical problems  Divide and conquer  Merge sort, Quick sort  Tree traversal  File scan / search  … [a, b, c, d, e, f, g, h] [a, b, c, d] [e, f, g, h] [a, b] [c, d] [e, f] [g, h]
14. Thread Pool Tasks Worker threads Queue
15. Thread Pool Contention!
16. Fork/Join Thread Pool
17. Fork/Join Thread Pool Work stealing
18. Languages are either concurrent or obsolete.
19. Java 5 Asynchronous calculations
20. Java 7 Asynchronous calculations Fork/Join
21. Java 8 Asynchronous calculations Fork/Join Parallel collections
22. Scala Asynchronous calculations Fork/Join Parallel collections Actors
23. Clojure Asynchronous calculations Fork/Join Parallel collections Actors Agents, Stm
24. Oz Asynchronous calculations Fork/Join Parallel collections Actors Agents, Stm Dataflow
25. Google's Go Asynchronous calculations Fork/Join Parallel collections Actors Agents, Stm Dataflow CSP
26. Asynchronous calculations Fork/Join Parallel collections Actors Agents, Stm Dataflow CSP
27. Asynchronous calculations Fork/Join Parallel collections Actors Agents, Stm Dataflow CSP Agenda
28. Actors Processes with a mail-box Share no data Communicate by sending messages Use a thread-pool
29. Stateless Actors (pure Java) class MyActor extends DynamicDispatchActor { Account account = ... public void onMessage(String msg) { String encripted = encrypt(msg); reply(encripted); } public void onMessage(Integer number) { reply(2 * number); } public void onMessage(Money cash) { System.out.println("Received a donation " + cash); account.deposit(cash); } }
30. Active Objects @ActiveObject class MyCounter { private int counter = 0 @ActiveMethod def incrementBy(int value) { println "Received an integer: $value" this.counter += value } }
31. Composing async functions int hash1 = hash(download('http://www.gpars.org')) int hash2 = hash(loadFile('/gpars/website/index.html')) boolean result = compare(hash1, hash2) println result
32. Composing async functions @AsyncFun hash = oldHash @AsyncFun compare = oldCompare @AsyncFun download = oldDownload @AsyncFun loadFile = oldLoadFile def hash1 = hash(download('http://www.gpars.org')) def hash2 = hash(loadFile('/gpars/website/index.html')) def result = compare(hash1, hash2) println result.get()
33. Composing async functions @AsyncFun hash = oldHash @AsyncFun(blocking = true) compare = oldCompare @AsyncFun download = oldDownload @AsyncFun loadFile = oldLoadFile def hash1 = hash(download('http://www.gpars.org')) def hash2 = hash(loadFile('/gpars/website/index.html')) boolean result = compare(hash1, hash2) println result
34. int hash(String text) {…} Promise<int> hash(Promise<String> | String text)
35. int hash(String text) {…} Promise<int> hash(Promise<String> | String text) compare( hash( download() ), hash( loadFile() ) )
36. int hash(String text) {…} Promise<int> hash(Promise<String> | String text) { 1.Return a Promise for the result 2.Wait (non-blocking) for the text param 3.Call the original hash() 4.Bind the result }
37. Composing async functions Combine functions as usual Parallelism is detected automatically
38. Dataflow Concurrency  No race-conditions  No live-locks  Deterministic deadlocks Completely deterministic programs BEAUTIFUL code (Jonas Bonér)
39. Dataflow Variables / Promises main task2 task3 x y z task1
40. Dataflows def df = new Dataflows() task { df.z = df.x + df.y } task { df.x = 10 } task { println ”I am task 3” df.y = 5 } assert 15 == df.z
41. operator(inputs: [headers, bodies, footers], outputs: [articles, summaries]) {header, body, footer -> def article = buildArticle(header, body, footer) bindOutput(0, article) bindOutput(1, buildSummary(article)) } * + <> Dataflow Operators
42. Url resolver Url resolver Downloader Groovy scanner Scala scanner Url resolver Url resolver Reporter Speculator Evaluator Splitter Confirm Cache updates Approvals Dataflow Operators
44. 'coz concurrency is Groovy Find more at: http://gpars.codehaus.org http://www.jroller.com/vaclav http://twitter.com/vaclav_pech GPars