User Settable Number of Cores

[jsnguyen]

As far as I can tell, there isn't a way for the user to set the number of cores used in the FFT.

I've tried using os.sched_setaffinity but this isn't a great way of doing this because you can only set specific cores. This overrides the CPU scheduler and ends up being very slow and doesn't scale very well at all unless you use all the cores on the system.

My particular use case is that I'm running HCIPy on a shared use server with a bunch of cores, and I need to be able to limit the number of threads used by my processes.

Probably need to change the file here.