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From aaron morton <>
Subject Re: Cassandra Memory Trend - increased memory usage when node idles.
Date Sun, 21 Aug 2011 10:42:20 GMT
Using memory allocated to the JVM is not really a problem unless it's OOM'ing. Or running into
performance issues due to excessive GC. 

One scenario I could imagine is a timeout triggered on a dirty memtable, this resulted in
a flush, the flush resulted in a minor compaction, the minor compaction read several SSTables,
the memory was used, the GC was been good and lazy.

200MB is a very small amount of memory, how much is allocated to the JVM Heap / how much does
the machine have?  


Aaron Morton
Freelance Cassandra Developer

On 20/08/2011, at 2:29 AM, Renato Bacelar da Silveira wrote:

> Hello All
> I have let a node run for a period of 2 hours, untouched, with something like
> 10 Column families, and just 30 columns in total.
> I see a memory trend that is continually increasing. There are no operations
> against that node.
> I started the node at 14:05, at 15:05 I did a manual GC.
> At 14:05, the node was GC'ed and reflected a 22MB memory footprint.
> At 15:05 the memory footprint was over 200MB. GC took footprint to 20MB+.
> At 16:05 the memory footprint was over 200MB again.
> Is there some way to stop the increased memory usage trend, when the node
> is left alone idling away like me on a Sunday morning??
> Regards
> -- 

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