Change process priority in Python, cross-platform

Question

I've got a Python program that does time-consuming computations. Since it uses high CPU, and I want my system to remain responsive, I'd like the program to change its priority to below-normal.

I found this: Set Process Priority In Windows - ActiveState

But I'm looking for a cross-platform solution.

Answer 1

On every Unix-like platform (including Linux and MacOsX), see os.nice here:

os.nice(increment)
Add increment to the process’s “niceness”. Return the new niceness. Availability: Unix.

Since you already have a recipe for Windows, that covers most platforms -- call os.nice with a positive argument everywhere but Windows, use that recipe there. There is no "nicely packaged" cross-platform solution AFAIK (would be hard to package this combo up, but, how much extra value would you see in just packaging it?-)

Answer 2

Here's the solution I'm using to set my process to below-normal priority:

lowpriority.py

def lowpriority():
    """ Set the priority of the process to below-normal."""

    import sys
    try:
        sys.getwindowsversion()
    except:
        isWindows = False
    else:
        isWindows = True

    if isWindows:
        # Based on:
        #   "Recipe 496767: Set Process Priority In Windows" on ActiveState
        #   http://code.activestate.com/recipes/496767/
        import win32api,win32process,win32con

        pid = win32api.GetCurrentProcessId()
        handle = win32api.OpenProcess(win32con.PROCESS_ALL_ACCESS, True, pid)
        win32process.SetPriorityClass(handle, win32process.BELOW_NORMAL_PRIORITY_CLASS)
    else:
        import os

        os.nice(1)

Tested on Python 2.6 on Windows and Linux.