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  1. JDK
  2. JDK-8310031

Parallel: Implement better work distribution for large object arrays in old gen

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    • gc
    • b21

        Currently Parallel GC young gc distributes work to find dirty cards on stripe basis (65k areas of memory): if an object starts in a stripe assigned to a thread, that thread owns that object to find dirty cards exclusively.

        This is a problem with large objArrays that limits parallelism: a single worker thread will own that objArray, limiting throughput.

        That should also fix the difference between parallel gc and g1 gc in pause times (4-5x+) for DelayInducer (JDK-8062128) found in JDK-8309960.

          1. BigArrayInOldGenRR.java
            1.0 kB
          2. card_scan_big_instances.java
            25 kB
          3. card_scan_scarce_2.java
            2 kB
          4. card_scan_scarce.java
            2 kB
          5. card_scan.java
            0.6 kB
          1.
          		 Release Note: Parallel: Precise Parallel Scanning of Large Object Arrays for Young Collection Roots Sub-task Resolved Richard Reingruber  

              rrich Richard Reingruber
              tschatzl Thomas Schatzl
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                Created:
                Updated:
                Resolved: