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From srmore <>
Subject Re: Cassandra high heap utilization under heavy reads and writes.
Date Wed, 27 Nov 2013 16:58:47 GMT
So, I did a lot of dial turning and heap tuning (came across this nice
writeup about JVM tuning still no luck
with 1.2.9. I gave up and upgraded to 1.2.12 and since then things are much
much better. I don't run into the heap issue that I used to with 1.2.9.

1.2.12 also looks more stable and seems to work  for us.


On Mon, Nov 25, 2013 at 11:10 AM, Christopher J. Bottaro <> wrote:

> Yes, we saw this same behavior.
> A couple of months ago, we moved a large portion of our data out of
> Postgres and into Cassandra.  The initial migration was done in a
> "distributed" manner:  we had 600 (or 800, can't remember) processes
> reading from Postgres and writing to Cassandra in tight loops.  This caused
> the exact behavior you described.  We also did a read before a write.
> After we got through the initial data migration, our normal workload is
> *much* less writes (and reads for that matter) such that our cluster can
> easily handle it, so we didn't investigate further.
> -- C
> On Sat, Nov 23, 2013 at 10:55 PM, srmore <> wrote:
>> Hello,
>> We moved to cassandra 1.2.9 from 1.0.11 to take advantage of the off-heap
>> bloom filters and other improvements.
>> We see a lot of messages dropped under high load conditions. We noticed
>> that when we do heavy read AND write simultaneously (we read first and
>> check whether the key exists if not we write it) Cassandra heap increases
>> dramatically and then gossip marks the node down (as a result of high load
>> on the node).
>> Under heavy 'reads only' we don't see this behavior.  Has anyone seen
>> this behavior ? any suggestions.
>> Thanks !

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