[HADOOP-15124] Slow FileSystem.Statistics counters implementation

• 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
• Component/s: common
• Labels: common filesystem fs pull-request-available statistics
• Target Version/s: 3.5.0
• Assignee: Igor Dvorzhak
• Reporter: Igor Dvorzhak
• Created: 17/Dec/17 17:11
• Updated: 23/Jun/24 12:55

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.

Issue Links

• is related to: HADOOP-13065 Add a new interface for retrieving FS and FC Statistics
• links to: GitHub Pull Request #316
• links to: GitHub Pull Request #316