I don’t know the exact reason why either. And it could be specific to the applications I happened to test, all I can say is that 4 processes per processor worked out best for us.

Perhaps 1 process with 40 threads would have worked just as well, as a recent test showed 50 threads and 1 process per processor working well on a TG2 app that I was testing — and I don’t think we spent much time playing with the cherrypy thread-count in those earlier tests.

Thanks for your blog post. I am not sure I understand why you would need several processes on each CPU (unless it is a multi core cpu). I would naively expect that the optimal setting is about one process (with multiple threads) per core. Why is this not the case?

Best regards,
Jesper