Lars Hofhansl created HBASE-11695:
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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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