[jira] [Created] (HBASE-11695) PeriodicFlusher and WakeFrequency issues

["Lars Hofhansl (JIRA)" <ji...@apache.org>]

Lars Hofhansl created HBASE-11695:
-------------------------------------

             Summary: PeriodicFlusher and WakeFrequency issues
                 Key: HBASE-11695
                 URL: https://issues.apache.org/jira/browse/HBASE-11695
             Project: HBase
          Issue Type: Bug
    Affects Versions: 0.94.21
            Reporter: Lars Hofhansl


We just ran into a flush storm caused by the PeriodicFlusher.
Many memstore became eligible for flushing at exactly the same time, the effect we've seen is that the exact same region was flushed multiple times, because the flusher wakes up too often (every 10s). The jitter of 20s is larger than that and it takes some time to actually flush the memstore.

Here's one example. We've seen 100's of these, monopolizing the flush queue and preventing "important" flushes from happening.

{code}
06-Aug-2014 20:11:56  [regionserver60020.periodicFlusher] INFO  org.apache.hadoop.hbase.regionserver.HRegionServer[1397]-- regionserver60020.periodicFlusher requesting flush for region tsdb,\x00\x00\x0AO\xCF* \x00\x00\x01\x00\x01\x1F\x00\x00\x03\x00\x00\x0C,1340147003629.ef4a680b962592de910d0fdeb376dfc2. after a delay of 13449
06-Aug-2014 20:12:06  [regionserver60020.periodicFlusher] INFO  org.apache.hadoop.hbase.regionserver.HRegionServer[1397]-- regionserver60020.periodicFlusher requesting flush for region tsdb,\x00\x00\x0AO\xCF* \x00\x00\x01\x00\x01\x1F\x00\x00\x03\x00\x00\x0C,1340147003629.ef4a680b962592de910d0fdeb376dfc2. after a delay of 14060
{code}

So we need to increase the period of the PeriodicFlusher to at least the random jitter, also increase the default random jitter (20s does not help with many regions).




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