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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-3796) Speed up edit log tests by avoiding fsync()
Date Mon, 13 Aug 2012 22:32:38 GMT
Todd Lipcon created HDFS-3796:
---------------------------------

             Summary: 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


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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