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Posted to common-issues@hadoop.apache.org by "Igor Dvorzhak (JIRA)" <ji...@apache.org> on 2017/12/17 17:12:00 UTC

[jira] [Created] (HADOOP-15124) Slow FileSystem.Statistics counters

Igor Dvorzhak created HADOOP-15124:
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             Summary: Slow FileSystem.Statistics counters 
                 Key: HADOOP-15124
                 URL: https://issues.apache.org/jira/browse/HADOOP-15124
             Project: Hadoop Common
          Issue Type: Bug
          Components: common
    Affects Versions: 3.0.0, 2.7.5, 2.8.3, 2.9.0
            Reporter: Igor Dvorzhak


While profiling 1TB TeraGen on Hadoop 2.8.2 cluster (Google Dataproc, 2 workers, GCS connector) I saw that FileSystem.Statistics code paths Wall time is 5.58% and CPU time is 26.5% of total execution time.

After switching FileSystem.Statistics implementation to LongAdder consumed Wall time decreased to 0.006% and CPU time to 0.104% of total execution time.

Total runtime decreased from 66 mins to 61 mins.

These results are not conclusive, because I didn't benchmark multiple times to average results, but regardless of performance gains switching to LongAdder simplifies code and reduces its complexity.



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