JavaZone 2019: Garbage Collectors for busy Java developers

Which Garbage collectors save you more money in the Cloud? What's the difference between a Serial and a Parallel GC? What is Shenandoah and why is so good? Do you know which GC you are using daily?
A quick visual overview on the Java Garbage collectors, the GC will be explained in plain English without Statistical formulas.

Transcript

1. Marco Molteni
   

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2. 3 7
   

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3. Supported Experimental Deprecated (but included)
   G1
   Z
   Shenandoah
   Epsilon
   Non-
   concurrent
   Concurrent
   No-ops
   Java 8
   Serial
   Parallel
   Java 12
   CMS
   4 7
   

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4. Supported Experimental Deprecated (but included)
   G1
   Z
   Shenandoah
   Epsilon
   Non-
   concurrent
   Concurrent
   No-ops
   Java 8
   Serial
   Parallel
   Java 12
   CMS
   4 3
   

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6. No collector
   satisfies every
   requirement
   Vertically scalable
   High throughput
   Low latency
   Low footprint
   

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8. App Thread App Thread
   GC Thread
   Pause
   GC Thread
   App Thread App Thread App Thread
   Pause Pause
   

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9. High Throughput
   Low footprint Scalable
   Low latency
   Non-Concurrent
   (Parallel, Serial)
   Concurrent (G1,
   Shenandoah, Z)
   

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11. Parallel
    GC
    App Thread
    GC
    Serial
    App Thread
    Serverless functions.
    Microdevices.
    Batch jobs.
    

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13. Parallel
    Serial
    G1
    Z
    Shenandoah
    

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14. Java 9
    JEP 248: Make G1 the Default Garbage Collector
    

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15. Ultra-short pauses (<10 ms).
    Scalable to TB of heap.
    Experimental.
    

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16. Red Hat Oracle
    Lead
    Platforms
    Production ready
    Platform
    independent
    Linux only
    Java 8u, 11u only
    RedHat builds
    Experimental only
    

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18. Shenandoah G1 & Serial Parallel
    Z (Java 13)
    Allocated Heap
    Used Heap
    

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19. …
    

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20. No GC activities.
    Great for tests.
    Epsilon
    

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21. Man kan ikke få både i pose og sekk
    Garbage Collectors = Tradeoff.
    The best collector is the one that works the well
    for YOUR application, not the one suggested in
    Stack Overflow / benchmarks.
    

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