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  1. JDK
  2. JDK-8230706

Waiting on completion of strong nmethod processing causes long pause times with G1

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    • gc
    • b21

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        On our internal Cassandra benchmark setup once or twice per run pause times are exceptionally long.

        This seems to be always caused by one thread in the Thread Roots scan phase, i.e. the log for that phase looks as follows:

        [2019-09-05T13:22:07.788+0100][942.036s][1567686127788ms][trace][gc,phases ] GC(271) Thread Roots (ms): Min: 0.0, Avg: 85.2, Max: 1954.3, Diff: 1954.3, Sum: 1959.1, Workers: 23
        [2019-09-05T13:22:07.788+0100][942.036s][1567686127788ms][trace][gc,phases,task ] GC(271) 0.0 0.3 0.3 0.2 0.2 1.0 0.3 1954.3 0.2 0.2 0.2 0.3 0.2 0.3 1.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

        Seems to occur since JDK11 (not jdk8u231 at least), and only seen G1, not others like ZGC.

        On that setup, THP is off, and also occurs if logs are created on a ramdisk. Sys time is zero.

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                tschatzl Thomas Schatzl
                tschatzl Thomas Schatzl
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