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stack commented on HBASE-15453: ------------------------------- JDK7 is dead. > [Performance] Considering reverting HBASE-10015 - reinstate synchronized in > StoreScanner > ---------------------------------------------------------------------------------------- > > Key: HBASE-15453 > URL: https://issues.apache.org/jira/browse/HBASE-15453 > Project: HBase > Issue Type: Improvement > Components: Performance > Reporter: Lars Hofhansl > Assignee: Lars Hofhansl > Priority: Critical > Attachments: 15453-0.98.txt > > > In HBASE-10015 back then I found that intrinsic locks (synchronized) in > StoreScanner are slower that explicit locks. > I was surprised by this. To make sure I added a simple perf test and many > folks ran it on their machines. All found that explicit locks were faster. > Now... I just ran that test again. On the latest JDK8 I find that now the > intrinsic locks are significantly faster: > (OpenJDK Runtime Environment (build 1.8.0_72-b15)) > Explicit locks: > 10 runs mean:2223.6 sigma:72.29412147609237 > Intrinsic locks: > 10 runs mean:1865.3 sigma:32.63755505548784 > I confirmed the same with timing some Phoenix scans. We can save a bunch of > time by changing this back > Arrghhh... So maybe it's time to revert this now...? > (Note that in trunk due to [~ram_krish]'s work, we do not lock in > StoreScanner anymore) > I'll attach the perf test and a patch that changes lock to synchronized, if > some folks could run this on 0.98, that'd be great. -- This message was sent by Atlassian JIRA (v6.3.4#6332)