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From Jonathan Ellis <>
Subject Re: 0.6.5 OOM during high read load
Date Sun, 20 Mar 2011 23:36:49 GMT
0.7.1+ uses zero-copy reads in mmap'd mode so having 80k references to
the same column is essentially just the reference overhead.

On Fri, Mar 18, 2011 at 7:11 PM, Dan Retzlaff <> wrote:
> Dear experts, :)
> Our application triggered an OOM error in Cassandra 0.6.5 by reading the
> same 1.7MB column repeatedly (~80k reads). I analyzed the heap dump, and it
> looks like the column value was queued 5400 times in an
> OutboundTcpConnection destined for the Cassandra instance that received the
> client request. Unfortunately, this intra-node connection goes across a
> 100Mb data center interconnect, so it was only a matter of time before the
> heap was exhausted.
> Is there something I can do (other than change the application behavior) to
> avoid this failure mode? I'm not the first to run into this, am I?
> Thanks,
> Dan

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support

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