Kihwal Lee created YARN-202:
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Summary: Log Aggregation generates a storm of fsync() for namenode
Key: YARN-202
URL: https://issues.apache.org/jira/browse/YARN-202
Project: Hadoop YARN
Issue Type: Bug
Affects Versions: 0.23.4, 2.0.2-alpha
Reporter: Kihwal Lee
Priority: Critical
When the log aggregation is on, write to each aggregated container log causes
hflush() to be called. For large clusters, this can creates a lot of fsync()
calls for namenode.
We have seen 6-7x increase in the average number of fsync operations compared
to 1.0.x on a large busy cluster. Over 99% of fsync ops were for log
aggregation writing to tmp files.
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