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  1. JDK
  2. JDK-8231932

Shenandoah: conc/par GC threads ergonomics overrides user settings

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    • gc
    • b18

    Description

      Seen with serviceability/sa/ClhsdbFlags.java, which sets ParallelGCThreads=1. Then Shenandoah heuristics acts and sets ConcGCThreads=2. Then Shenandoah adjustment kicks in, figures ParallelGCThreads < ConcGCThreads, and bumps ParallelGCThreads to 2, overriding the user setting and failing the test.

      $ CONF=linux-x86_64-server-fastdebug make images run-test TEST=serviceability/sa/ClhsdbFlags.java TEST_VM_OPTS="-XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC"

      hashCode = 5 default
      ]
       exitValue = -1

       LingeredApp stdout: [];
       LingeredApp stderr: [OpenJDK 64-Bit Server VM warning: Shenandoah expects ConcGCThreads <= ParallelGCThreads, adjusting ParallelGCThreads automatically
      ]
       LingeredApp exitValue = 0
      java.lang.RuntimeException: Test ERROR java.lang.RuntimeException: 'ParallelGCThreads = 1' missing from stdout/stderr

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              shade Aleksey Shipilev
              shade Aleksey Shipilev
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