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From Peter Schuller <peter.schul...@infidyne.com>
Subject Re: Cassandra benchmarking on Rackspace Cloud
Date Mon, 19 Jul 2010 19:16:52 GMT
> stress.py uses multiprocessing if it is present, circumventing the GIL; we ran the tests
with python 2.6.5.

Ah, sorry about that. I was mis-remembering because I had to use
threading with pystress because multiprocessing was broken/unavailabie
(can't remember which) on FreeBSD.

I agree with Stu's point that if you're using a fixed concurrency of
50, you'd expect to see a fixed maximum throughput. Even with an
infinite capacity in the cassandra cluster, you'll have some
particular latency associated with each request. Having exactly 50
internally sequential clients performing reads, this yields some
particular maximum throughput which won't be affected by a larger
cassandra cluster.

The only way to see higher total throughput is to have a higher total
concurrency, or to make each individual request have lower latency.
The former would scale, while the latter wouldn't.

-- 
/ Peter Schuller

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