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From David Schoonover <>
Subject Re: Cassandra benchmarking on Rackspace Cloud
Date Mon, 19 Jul 2010 18:02:00 GMT uses multiprocessing if it is present, circumventing the GIL; we ran the tests with
python 2.6.5.

David Schoonover

On Jul 19, 2010, at 1:51 PM, Peter Schuller wrote:

>>> One with 50 threads; it is remote from the cluster but within the same
>>> DC in both cases. I also run the test with multiple clients and saw
>>> similar results when summing the reqs/sec.
>> Multiple client processes, or multiple client machines?
> In particular, note that the way CPython works, if you're CPU bound
> across many threads, you're constantly hitting the worst possible
> scenario with respect to wasting CPU cycles on multiple cores (due to
> the extremely contended GIL). While I'd still expect to see an
> increase in throughput from running multiple separate processes on the
> same (multi-core) machine, I really wouldn't be too sure. Even with
> supposedly idle CPU you may still be bottlenecking on the client
> depending on scheduling decisions in the kernel.
> -- 
> / Peter Schuller

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