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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ACCUMULO-2801) define tablet syncs walog for each tablet in a batch
Date Tue, 13 May 2014 18:50:14 GMT
Keith Turner created ACCUMULO-2801:
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             Summary: define tablet syncs walog for each tablet in a batch
                 Key: ACCUMULO-2801
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2801
             Project: Accumulo
          Issue Type: Bug
    Affects Versions: 1.6.0, 1.5.1, 1.5.0
            Reporter: Keith Turner


When the batch writer sends a batch of mutations for N tablets that were not currently using
a walog, then define tablet will be called for each tablet.  Define tablet will sync the walog.
  In hadoop 2 hsync is used, which is much slower than hadoop1 sync calls.  If hsync takes
50ms and there are 100 tablets, then this operation would take 5 secs.  The calls to define
tablet do not occur frequently, just when walogs switch or tablets are loaded so the cost
will be amortized.  Ideally there could be one walog sync call for all of the tablets in a
batch of mutations.



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