[ https://issues.apache.org/jira/browse/HADOOP-10681?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Gopal V updated HADOOP-10681: ----------------------------- Summary: Remove synchronized blocks from SnappyCodec and ZlibCodec buffering (was: Compressor inner methods are all synchronized - within a tight loop) > Remove synchronized blocks from SnappyCodec and ZlibCodec buffering > ------------------------------------------------------------------- > > Key: HADOOP-10681 > URL: https://issues.apache.org/jira/browse/HADOOP-10681 > Project: Hadoop Common > Issue Type: Bug > Components: performance > Affects Versions: 2.2.0, 2.4.0, 2.5.0 > Reporter: Gopal V > Assignee: Gopal V > Labels: perfomance > Attachments: compress-cmpxchg-small.png, perf-top-spill-merge.png > > > The current implementation of SnappyCompressor spends more time within the > java loop of copying from the user buffer into the direct buffer allocated to > the compressor impl, than the time it takes to compress the buffers. > !perf-top-spill-merge.png! > The bottleneck was found to be java monitor code inside SnappyCompressor. > The methods are neatly inlined by the JIT into the parent caller > (BlockCompressorStream::write), which unfortunately does not flatten out the > synchronized blocks. > !compress-cmpxchg-small.png! > The loop does a write of small byte[] buffers (each IFile key+value). > I counted approximately 6 monitor enter/exit blocks per k-v pair written. -- This message was sent by Atlassian JIRA (v6.2#6252)