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From Peter Schuller <>
Subject Re: Follow-up post on cassandra configuration with some experiments on GC tuning
Date Fri, 27 Aug 2010 07:05:57 GMT
> Any reason not to add the incremental mode settings?  It's unusual to
> see a Cassandra node out of CPU, but wild heap oscillations are pretty
> common.

FWIW, while I have never tried it with Cassandra, the CMS incremental
mode has never ever worked well for me when I have applied it to
anything that stresses the GC (but these have been small test cases,
not real software). Typically it's just not doing the incremental duty
cycles aggressively enough and you end up falling back to full gc.

Whether or not this is likely to happen with Cassandra I don't know. I
don't know much about the incremental duty cycles are scheduled and it
may be the case that Cassandra is not even remotely close to having a
problem with incremental mode. But I would suggest caution and testing
prior to making it the default.

/ Peter Schuller

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