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From aaron morton <>
Subject Re: Reducing memory footprint
Date Wed, 09 Mar 2011 20:35:39 GMT
	 It sounds like the JVM is behaving. Perhaps turn off mmapped disk_access to double check
that the number you are seeing as resident does not include the mapped memory?


On 10/03/2011, at 6:36 AM, Jonathan Ellis wrote:

> I edited Peter Schuller's reply last time this came up into a FAQ:
> On Wed, Mar 9, 2011 at 11:10 AM, Casey Deccio <> wrote:
>> On Sat, Mar 5, 2011 at 7:37 PM, aaron morton <>
>> wrote:
>>> There is some additional memory usage in the JVM beyond that Heap size, in
>>> the permanent generation. 900mb sounds like too much for that, but you can
>>> check by connecting with JConsole and looking at the memory tab. You can
>>> also check the heap size there to see that it's under the value you've set.
>> Thanks for the tip!
>> From JConsole:
>> Heap memory usage: Current 46M; Max 902M
>> Non-Heap memory usage: Current 34M; Max 200MB
>> Both of these seem reasonable and don't reach the (current) 2.1 GB resident
>> usage I am seeing.
>>> Check you are using standard disk access (in conf/cassandra.yaml) rather
>>> than memory mapped access. However the memory mapped memory is reported as
>>> virtual memory, not resident. So I'm just mentioning it to be complete.
>> At the moment, it's set to "auto", but it's a 64-bit machine, so I believe
>> it's using memory mapped.  The virtual memory usage says that it is 54.6 GB.
>>> If you think you've configured things correctly and the JVM is not
>>> behaving (which is unlikely) please include some information on the JVM and
>>> OS versions and some hard numbers about what the process is using.
>> Debian 6.0 using openjdk-6-jre-lib-6b18-1.8.3-2+squeeze1
>> Thanks for your help.
>> Casey
> -- 
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support

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