[jira] [Created] (CASSANDRA-7926) Stress can OOM on merging of timing samples

["Benedict (JIRA)" <ji...@apache.org>]

Benedict created CASSANDRA-7926:
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             Summary: Stress can OOM on merging of timing samples
                 Key: CASSANDRA-7926
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7926
             Project: Cassandra
          Issue Type: Improvement
          Components: Tools
            Reporter: Benedict
            Assignee: Benedict
            Priority: Minor
             Fix For: 2.1.1


{noformat}
Exception in thread "StressMetrics:2" java.lang.OutOfMemoryError: Java heap space
        at java.util.Arrays.copyOf(Arrays.java:2343)
        at org.apache.cassandra.stress.util.SampleOfLongs.merge(SampleOfLongs.java:76)
        at org.apache.cassandra.stress.util.TimingInterval.merge(TimingInterval.java:95)
        at org.apache.cassandra.stress.util.Timing.snapInterval(Timing.java:95)
        at org.apache.cassandra.stress.StressMetrics.update(StressMetrics.java:124)
        at org.apache.cassandra.stress.StressMetrics.access$200(StressMetrics.java:36)
        at org.apache.cassandra.stress.StressMetrics$1.run(StressMetrics.java:72)
        at java.lang.Thread.run(Thread.java:744)
{noformat}

This is partially down to recently increasing the per-thread sample size, but also because we allocate temporary space linear in size to total sample size in all threads during merge. This can easily be avoided. We should also scale per-thread sample size based on total number of threads, so we limit total memory use.



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