> Well, even with greenlets, I assume you're using at least one FD
(socket) per client, no?
> So you can get EMFILE on socket() just as on os.urandom(). 

I do many calls on urandom() so that's the FD bottleneck.

> So os.urandom() isn't your biggest problem here.

Of course it is. But it looks like you know better without having looked at the code. :)

> I'd suggest you to just open '/dev/urandom' once, 
> and then make all your threads/green-threads read from it.

Let me know how to do this without being able to prevent the API to close the FD everytime.

> IMO os.urandom() is a really poor API ;-)

Then we should improve it or deprecate it.