[HADOOP-15124] Slow FileSystem.Statistics counters implementation - ASF JIRA

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Details

Type: Sub-task
Status: Patch Available
Priority: Major
Resolution: Unresolved
Affects Version/s: 2.9.0, 2.8.3, 2.7.5, 3.0.0, 3.1.0
Fix Version/s: None
Component/s: common
Labels:

Target Version/s:

3.5.0

Description

While profiling 1TB TeraGen job 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 job 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.