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From Jonathan Ellis <>
Subject Re: Reducing memory footprint
Date Wed, 09 Mar 2011 17:36:36 GMT
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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