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https://issues.apache.org/jira/browse/HADOOP-7255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13028039#comment-13028039
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Bharath Mundlapudi commented on HADOOP-7255:
--------------------------------------------
Thanks for posting performance data. Can you please let us know the test setup
details? Like how big is your cluster?
It is interesting to see high Std Deviation without the patch. Did you try
multiple runs?
> Performance regression bug caused by locking code
> -------------------------------------------------
>
> Key: HADOOP-7255
> URL: https://issues.apache.org/jira/browse/HADOOP-7255
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 0.20.203.0
> Reporter: T Jake Luciani
>
> While testing the 0.20.203 branch we have discovered quite a severe
> performance regression caused by the following checkin:
> http://svn.apache.org/viewvc?view=revision&revision=1079260
> This locking seems to cause a pause of a few seconds between tasks, example
> with DFSIOTest:
> *CURRENT CODE*
> {noformat}
> 11/05/02 21:16:28 INFO fs.TestDFSIO: ----- TestDFSIO ----- : read
> 11/05/02 21:16:28 INFO fs.TestDFSIO: Date & time: Mon May 02
> 21:16:28 EDT 2011
> 11/05/02 21:16:28 INFO fs.TestDFSIO: Number of files: 5
> 11/05/02 21:16:28 INFO fs.TestDFSIO: Total MBytes processed: 500
> 11/05/02 21:16:28 INFO fs.TestDFSIO: Throughput mb/sec: 303.3980582524272
> 11/05/02 21:16:28 INFO fs.TestDFSIO: Average IO rate mb/sec:
> 327.69122314453125
> 11/05/02 21:16:28 INFO fs.TestDFSIO: IO rate std deviation: 78.95767116969083
> 11/05/02 21:16:28 INFO fs.TestDFSIO: Test exec time sec: 19.476
> 11/05/02 21:16:28 INFO fs.TestDFSIO:
> {noformat}
> *WITH PATCH REMOVED*
> {noformat}
> 11/05/02 21:19:03 INFO fs.TestDFSIO: ----- TestDFSIO ----- : read
> 11/05/02 21:19:03 INFO fs.TestDFSIO: Date & time: Mon May 02
> 21:19:03 EDT 2011
> 11/05/02 21:19:03 INFO fs.TestDFSIO: Number of files: 5
> 11/05/02 21:19:03 INFO fs.TestDFSIO: Total MBytes processed: 500
> 11/05/02 21:19:03 INFO fs.TestDFSIO: Throughput mb/sec:
> 366.03221083455344
> 11/05/02 21:19:03 INFO fs.TestDFSIO: Average IO rate mb/sec:
> 366.35528564453125
> 11/05/02 21:19:03 INFO fs.TestDFSIO: IO rate std deviation:
> 11.020931463080379
> 11/05/02 21:19:03 INFO fs.TestDFSIO: Test exec time sec: 3.543
> 11/05/02 21:19:03 INFO fs.TestDFSIO:
> {noformat}
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