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From Time Less <timelessn...@gmail.com>
Subject Re: Memory usage continually increases with reads
Date Wed, 28 Apr 2010 22:28:51 GMT
This sounds similar to /proc/sys/vm/swappiness misconfiguration. Is it zero
or close to zero? If setting it 0 solves your problem, make sure all your
nodes get this:

/etc/sysctl.conf:
  vm.swappiness=0


On Wed, Apr 28, 2010 at 12:12 PM, Kyusik Chung <kyusik@discovereads.com>wrote:

> Hello.  I am using Cassandra 0.6.1 on ubuntu 8.04.  3 node cluster.
>
> I notice that when I start making lots of read requests (serially), memory
> usage of jsvc keeps climbing until it uses up all memory on the server
> (happens for all 3 servers in the cluster).  At that point, the box starts
> swapping a little (but not too much) and performance is degraded.  Read
> performance does not drop off a cliff, but it does take a serious hit (maybe
> 50%).
>
> I have tried setting Xmx to various different values, but it doesnt seem to
> limit the growth in memory usage.  I understand that I should expect to see
> jsvc use a bit more memory than what the jvm is configured to use, but it
> doesnt seem to be limited to just an overhead.  I have set Xmx all the way
> down to 128M (just to test) and still jsvc will use up 2G of memory.
>
> Are there other settings that I should be changing?
>
> Note that when I test by simply running a lot of writes but no reads, jsvc
> seems to respect the Xmx value.
>
> Thanks!
>
> Kyusik Chung


-- 
timeless(ness)

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