Jason Lowe created MAPREDUCE-5268:
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Summary: Improve history server startup performance
Key: MAPREDUCE-5268
URL: https://issues.apache.org/jira/browse/MAPREDUCE-5268
Project: Hadoop Map/Reduce
Issue Type: Improvement
Components: jobhistoryserver
Affects Versions: 2.0.4-alpha, 0.23.7
Reporter: Jason Lowe
The history server can easily take many minutes to startup when there are a
significant number of jobs to scan in the done directory. However the scanning
of files is not the bottleneck, rather it's the heavy use of
ConcurrentSkipListMap.size in HistoryFileManager.
ConcurrentSkipListMap.size is a very expensive operation, especially on maps
with many entries, as it has to scan every entry to compute the size. We
should avoid calling this method or at least minimize its use.
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