Todd Lipcon created HDFS-13703:
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Summary: Avoid allocation of CorruptedBlocks hashmap when no
corrupted blocks are hit
Key: HDFS-13703
URL: https://issues.apache.org/jira/browse/HDFS-13703
Project: Hadoop HDFS
Issue Type: Improvement
Components: performance
Reporter: Todd Lipcon
Assignee: Todd Lipcon
The DFSClient creates a CorruptedBlocks object, which contains a HashMap, on
every read call. In most cases, a read will not hit any corrupted blocks, and
this hashmap is not used. It seems the JIT isn't smart enough to eliminate this
allocation. We would be better off avoiding it and only allocating in the rare
case when a corrupt block is hit.
Removing this allocation reduced CPU usage of a TeraValidate job by about 10%.
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