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From "Nicolas Liochon (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-11226) Document and increase the default value for hbase.hstore.flusher.count
Date Wed, 21 May 2014 16:34:40 GMT
Nicolas Liochon created HBASE-11226:

             Summary: Document and increase the default value for hbase.hstore.flusher.count
                 Key: HBASE-11226
                 URL: https://issues.apache.org/jira/browse/HBASE-11226
             Project: HBase
          Issue Type: Bug
          Components: regionserver
    Affects Versions: 0.98.2, 0.99.0
            Reporter: Nicolas Liochon
            Assignee: Nicolas Liochon
             Fix For: 0.99.0, 0.98.3

HBASE-6466 add the possibility to have multiple threads for the flusher.
The default value is 1, but this should be incremented to 2 reasons:
 - I've observed that the flush of a region can be delayed because another is in progress.
During a write load, this leads to an increased latency because the memstore size increases
and then block the client
 - if, by accident, a flusher hits a slow or bad datanode, all the flush will have to wait
until the timeouts expires. With 2 or more flushers and some luck the other regions will be
flushed by the second thread. 

Lastly this setting is important enough to be documented in the standard hbase site imho.

I think it's important enough to go in the .98 branch as well
There will be an impact: as the flush won't be queued (or less queued) we may have more compactions...

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