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https://issues.apache.org/jira/browse/HDFS-3796?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13433692#comment-13433692
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Suresh Srinivas commented on HDFS-3796:
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Todd, do multiple junit tests reuse JVM? If so, you are better off adding this
to @BeforeClass and @AfterClass?
> Speed up edit log tests by avoiding fsync()
> -------------------------------------------
>
> Key: HDFS-3796
> URL: https://issues.apache.org/jira/browse/HDFS-3796
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: test
> Affects Versions: 3.0.0, 2.2.0-alpha
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Minor
> Attachments: hdfs-3796.txt
>
>
> Our edit log tests are very slow because they incur a lot of fsyncs as they
> write out transactions. Since fsync() has no effect except in the case of
> power outages or system crashes, and we don't care about power outages in the
> context of tests, we can safely skip the fsync without any loss in coverage.
> In my tests, this sped up TestEditLog by about 5x. The testFuzzSequences test
> case improved from ~83 seconds with fsync to about 5 seconds without. These
> results are from my SSD laptop - they are probably even more drastic on
> spinning media.
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