> 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
