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From Brian Jeltema <>
Subject Re: hadoop inserts blow out heap
Date Thu, 13 Sep 2012 16:59:39 GMT
I didn't get a response to this, so I'll give it another shot. I tweaked some parameters and
cleaned up my schema.
My Hadoop/Cassandra job got further, but still dies with an OOM error. This time, the heap
dump displays
a JMXConfigurableThradPoolExecutor with a retained heap of 7.5G. I presume this means that
the Hadoop
job is writing to Cassandra faster than Cassandra can write to disk. Is there anything I can
do to throttle the job? The
Cassandra cluster is set up with default configuration values except for a reduced memtable

Forgot to mention this is Cassandra 1.1.2

Thanks in advance.


On Sep 12, 2012, at 7:52 AM, Brian Jeltema wrote:

> I'm a fairly novice Cassandra/Hadoop guy. I have written a Hadoop job (using the Cassandra/Hadoop
integration API)
> that performs a full table scan and attempts to populate a new table from the results
of the map/reduce. The read
> works fine and is fast, but the table insertion is failing with OOM errors (in the Cassandra
VM). The resulting heap dump from one node shows that
> 2.9G of the heap is consumed by a JMXConfigurableThreadPoolExecutor that appears to be
full of batch mutations.
> I'm using a 6-node cluster, 32G per node, 8G heap, RF=3, if any of that matters.
> Any suggestions would be appreciated regarding configuration changes or additional information
I might
> capture to understand this problem.
> Thanks
> Brian J

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