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From Peter Schuller <>
Subject Re: Cassandra benchmarking on Rackspace Cloud
Date Mon, 19 Jul 2010 17:51:47 GMT
>> 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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