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https://issues.apache.org/jira/browse/HDFS-2142?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Allen Wittenauer resolved HDFS-2142.
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Resolution: Cannot Reproduce
Stale.
> Namenode in trunk has much slower performance than Namenode in MR-279 branch
> ----------------------------------------------------------------------------
>
> Key: HDFS-2142
> URL: https://issues.apache.org/jira/browse/HDFS-2142
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 0.23.0
> Reporter: Eric Payne
>
> I am measureing the performance of the namenode by running the
> org.apache.hadoop.fs.loadGenerator.LoadGenerator application. This
> application shows there is a very large slowdown in the processing of opens,
> writes, closes, and operations per second in the trunk when compared to the
> MR-279 branch
> There have been some race conditions and locking issues fixed in trunk, which
> is a very good thing because these race conditions were causing the namenode
> to crash under load conditions (see HDFS:1257). However, the slowdown to the
> namenode is considerable.
> I am still trying to verify which changes caused the slowdown. It was
> originally suggested that the HDFS:988 may have caused the slowdown, but I
> don't think it was the culprit. I have checked out and built from SVN 3
> revisions previous to HDFS988 and they all have about the same performance.
> Here is my environment:
> Host0: namenode daemon
> Host1-9: simulate many datanodes using org.apache.hadoop.hdfs.DataNodeCluster
>
> LoadGenerator output on MR-279 branch:
> Average open execution time: 1.8496516782773909ms
> Average deletion execution time: 2.956340167046317ms
> Average create execution time: 3.725259427992913ms
> Average write_close execution time: 11.151860288534548ms
> Average operations per second: 1053.3666666666666ops/s
> LoadGenerator output on trunk:
> Average open execution time: 28.603515625ms
> Average deletion execution time: 32.20792079207921ms
> Average create execution time: 32.37326732673267ms
> Average write_close execution time: 82.84752475247525ms
> Average operations per second: 135.13333333333333ops/s
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