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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7255) Performance regression bug caused by locking code
Date Tue, 03 May 2011 11:35:03 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13028162#comment-13028162
] 

T Jake Luciani commented on HADOOP-7255:
----------------------------------------

For simplicity this is a single node from a fresh checkout.  Yes I did run this multiple times...
the stddev varies on read from 78 - 30... writes are fine in terms of stddev.

If you build the test jar you should be able to reproduce locally.

> 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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