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From Sean Bridges <sean.brid...@gmail.com>
Subject 10 minute cassandra pause
Date Wed, 23 Jun 2010 21:26:42 GMT
We were running a load test against a single 0.6.2 cassandra node.  24
hours into the test,  Cassandra appeared to be nearly frozen for 10
minutes.  Our write rate went to almost 0, and we had a large number
of write timeouts.  We weren't swapping or gc'ing at the time.

It looks like the problems were caused by our memtables flushing after
24 hours (we have MemtableFlushAfterMinutes=1440).  Some of our column
families are written to infrequently so that they don't hit the flush
thresholds in MemtableOperationsInMillions and MemtableThroughputInMB.
 After 24 hours we had ~3000 commit log files.

Is this flushing causing Cassandra to become unresponsive?  I would
have thought Cassandra could flush in the background without blocking
new writes.

Thanks,

Sean

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