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From Vasileios Vlachos <vasileiosvlac...@gmail.com>
Subject Re: Cassandra running out of memory?
Date Thu, 12 Apr 2012 14:19:56 GMT
Hello Aaron,

Thank you for getting back to me.

I will change to m1.large first to see how long it will take Cassandra node
to die (if at all). If again not happy I will try more memory. I just want
to test it step by step and see what the differences are. I will also
change the cassandra-env file back to defaults.

Is there an absolute minimum requirement for Cassandra in terms of memory?
I might be wrong, but from my understanding we shouldn't have any problems
given the amount of data we store per day (currently approximately 2-2.5G /
day).

Thank you in advance,

Bill


On Wed, Apr 11, 2012 at 7:33 PM, aaron morton <aaron@thelastpickle.com>wrote:

> 'system_memory_in_mb' (3760) and the 'system_cpu_cores' (1) according to
> our nodes' specification. We also changed the 'MAX_HEAP_SIZE' to 2G and the
> 'HEAP_NEWSIZE' to 200M (we think the second is related to the Garbage
> Collection).
>
> It's best to leave the default settings unless you know what you are doing
> here.
>
> In case you find this useful, swap is off and unevictable memory seems to
> be very high on all 3 servers (2.3GB, we usually observe the amount of
> unevictable memory on other Linux servers of around 0-16KB)
>
> Cassandra locks the java memory so it cannot be swapped out.
>
> The problem is that the node we hit from our thrift interface dies
> regularly (approximately after we store 2-2.5G of data). Error message:
> OutOfMemoryError: Java Heap Space and according to the log it in fact used
> all of the allocated memory.
>
> The easiest solution will be to use a larger EC2 instance.
>
> People normally use an m1.xlarge with 16Gb of ram (you would also try an
> m1.large).
>
> If you are still experimenting I would suggest using the larger instances
> so you can make some progress. Once you have a feel for how things work you
> can then try to match the instances to your budget.
>
> Hope that helps.
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 11/04/2012, at 1:54 AM, Vasileios Vlachos wrote:
>
> Hello,
>
> We are experimenting a bit with Cassandra lately (version 1.0.7) and we
> seem to have some problems with memory. We use EC2 as our test environment
> and we have three nodes with 3.7G of memory and 1 core @ 2.4G, all running
> Ubuntu server 11.10.
>
> The problem is that the node we hit from our thrift interface dies
> regularly (approximately after we store 2-2.5G of data). Error message:
> OutOfMemoryError: Java Heap Space and according to the log it in fact used
> all of the allocated memory.
>
> The nodes are under relatively constant load and store about 2000-4000 row
> keys a minute, which are batched through the Trift interface in 10-30 row
> keys at once (with about 50 columns each). The number of reads is very low
> with around 1000-2000 a day and only requesting the data of a single row
> key. The is currently only one used column family.
>
> The initial thought was that something was wrong in the cassandra-env.sh
> file. So, we specified the variables 'system_memory_in_mb' (3760) and the
> 'system_cpu_cores' (1) according to our nodes' specification. We also
> changed the 'MAX_HEAP_SIZE' to 2G and the 'HEAP_NEWSIZE' to 200M (we think
> the second is related to the Garbage Collection). Unfortunately, that did
> not solve the issue and the node we hit via thrift keeps on dying regularly.
>
> In case you find this useful, swap is off and unevictable memory seems to
> be very high on all 3 servers (2.3GB, we usually observe the amount of
> unevictable memory on other Linux servers of around 0-16KB) (We are not
> quite sure how the unevictable memory ties into Cassandra, its just
> something we observed while looking into the problem). The CPU is pretty
> much idle the entire time. The heap memory is clearly being reduced once in
> a while according to nodetool, but obviously grows over the limit as time
> goes by.
>
> Any ideas? Thanks in advance.
>
> Bill
>
>
>

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