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Posted to user@cassandra.apache.org by Mikio Braun <mi...@cs.tu-berlin.de> on 2010/09/02 18:38:33 UTC
Re: Follow-up post on cassandra configuration with some experiments
on GC tuning
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Hi Carsten,
> In this regard, what I personally miss in Mikios - however nice - analysis, is what are the effects on the application stop times due to any garbage collection runs for the cases tested. In most cases, I prefer having low pauses due to any garbage collection runs and don't care too much about the shape of the memory usage, and I guess, that's the reason why the low pause collector is used by default for running cassandra.
I see your point. I haven't explicitly tested those pauses. You can get
them from the gc logs (with some amount of perl parsing).
Subjectively speaking, I saw a higher probability of timeouts if GC took
too long. One other thing to look out for would be CMS failures (when
you start a CMS cycle but the young generation GCs run out of memory to
promote objects) which then results in a full GC cycle.
Probably I can rerun the tests and save the gc logs as well and put them
somewhere.
- -M
- --
Dr. Mikio Braun email: mikio@cs.tu-berlin.de
TU Berlin web: ml.cs.tu-berlin.de/~mikio
Franklinstr. 28/29 tel: +49 30 314 78627
10587 Berlin, Germany
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