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Elliott Clark updated HBASE-5898: --------------------------------- Attachment: HBASE-5898-0.patch We saw this on a production cluster. A single data block was being requested by all ipc handlers. This caused a great deal of lock contention. Todd's patch fixed the issue and caused reads to go back to a normal duration. This patch is almost identical to Todd's patch. It makes the second try to get a block from the block cache not count as a miss. > Consider double-checked locking for block cache lock > ---------------------------------------------------- > > Key: HBASE-5898 > URL: https://issues.apache.org/jira/browse/HBASE-5898 > Project: HBase > Issue Type: Improvement > Components: Performance > Affects Versions: 0.94.1 > Reporter: Todd Lipcon > Assignee: Todd Lipcon > Priority: Critical > Attachments: 5898-TestBlocksRead.txt, HBASE-5898-0.patch, > hbase-5898.txt > > > Running a workload with a high query rate against a dataset that fits in > cache, I saw a lot of CPU being used in IdLock.getLockEntry, being called by > HFileReaderV2.readBlock. Even though it was all cache hits, it was wasting a > lot of CPU doing lock management here. I wrote a quick patch to switch to a > double-checked locking and it improved throughput substantially for this > workload. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira