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From Peter Schuller <peter.schul...@infidyne.com>
Subject Re: ParNew (promotion failed)
Date Sat, 26 Mar 2011 22:21:46 GMT
> So to resolve this i must tune young generation (HEAP_NEWSIZE) -Xmn, and
> tune in_memory_compaction_limit_in_mb config parameter?

More likely adjust the initial occupancy trigger and/or the heap size.
Probably just the latter. This is assuming you're on 0.7 with mostly
default JVM options. See cassandra-env.sh.

In fact, you may even be helped by *decreasing* the young generation
size if you're running a version which has a cassandra-env which
specifies -Xmn. I'm not entirely sure because I don't know off hand
exactly based on what the occupancy trigger is happening, but the
young gen is large and the workload is such that young-gen gc:s
promote a high percentage of it's data, I suspect that can lead to CMS
triggering too late.  (So this paragraph is speculation.)

-- 
/ Peter Schuller

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