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From Kyusik Chung <>
Subject Memory usage continually increases with reads
Date Wed, 28 Apr 2010 19:12:43 GMT
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.


Kyusik Chung
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