Details
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Bug
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Status: Closed
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Minor
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Resolution: Invalid
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0.94.21
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None
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None
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None
Description
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.
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
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).