Maximum number of threads

Michael Fuhr mfuhr at
Wed Sep 29 09:50:34 EDT 2004

Kirby Angell <kangell at> writes:

> We are porting our applications from Python 2.2 on RH9 to Python 2.3 on 
> RH9.  One of our apps used to be able to create threads with wild 
> abandon, 800 or more if necessary.  With Python 2.3 we are hitting a 
> hard limit of 254 on RH9 and around 400 on FC2.

What happens when you hit this "hard limit"?  If there's an error
message then it might hint at the problem.

> What is the limiting factor for the number of threads we can create?  Is 
> there a way to increase it?

I'm not current on Linux threading models -- do these versions of
Linux create a new process for each thread?  If so, could resource
limits be preventing you from creating more threads?

Michael Fuhr

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