> '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
