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Todd Lipcon commented on HDFS-13703: ------------------------------------ BTW would be better if we could entirely avoid allocating the CorruptedBlocks structure at all, but couldn't see a straightforward way of doing that, especially for pread. > 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 > Priority: Major > Attachments: hdfs-13703.patch > > > 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%. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org