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From aaron morton <aa...@thelastpickle.com>
Subject Re: Native heap leaks?
Date Thu, 05 May 2011 23:16:23 GMT
Hannes, 
	To get a baseline of behaviour set disk_access to standard. You will probably want to keep
it like that if you want better control over the memory on the box. 

	Also connect to the box with JConsole and look at the PermGen space used it is not included
in the max heap space setting. You can also check the heap usage there, running inside of
1G is very tricky. 

	If you want to keep it inside of 2Gb trying setting the heap max to 1.5G, use standard IO,
disable caches, and use a low memtable threshold (it depends on how many CF's you have, try
32mb)

Hope that helps.
	
-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 5 May 2011, at 22:30, Hannes Schmidt wrote:

> This was my first thought, too. We switched to mmap_index_only and
> didn't see any change in behavior. Looking at the smaps file attached
> to my original post, one can see that the mmapped index files take up
> only a minuscule part of RSS.
> 
> On Wed, May 4, 2011 at 11:37 PM, Oleg Anastasyev <oleganas@gmail.com> wrote:
>> Probably this is because of mmapped io access mode, which is enabled by default
>> in 64-bit VMs - RAM is occupied by data files.
>> If you have such a tight memory reqs, you can turn on standard access mode in
>> storage-conf.xml, but dont expect it to work fast then:
>> <!--
>> 
>> 
>>  ~ Access mode.  mmapped i/o is substantially faster, but only practical on
>> 
>> 
>>  ~ a 64bit machine (which notably does not include EC2 "small" instances)
>> 
>> 
>>  ~ or relatively small datasets.  "auto", the safe choice, will enable
>> 
>> 
>>  ~ mmapping on a 64bit JVM.  Other values are "mmap", "mmap_index_only"
>> 
>> 
>>  ~ (which may allow you to get part of the benefits of mmap on a 32bit
>> 
>> 
>>  ~ machine by mmapping only index files) and "standard".
>> 
>> 
>>  ~ (The buffer size settings that follow only apply to standard,
>> 
>> 
>>  ~ non-mmapped i/o.)
>> 
>> 
>>  -->
>> 
>> 
>>  <DiskAccessMode>standard</DiskAccessMode>
>> 
>> 


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