High CPU usage in pygame

[illume]

Originally reported by: Maksym Planeta (Bitbucket: mplaneta, GitHub: mplaneta)

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Hello,

I have a following snippet of code:

#!python


pygame.init()
import time
time.sleep(50)

When the scripts goes sleep, I observe high CPU utilization.

I tracked this down to sound system, and when I add pygame.mixer.quit() after init, script utilizes CPU as expected. I figured out that pygame creates a new process, which eats up all the CPU and the backtrace of this thread looks as follows (this is how I pointed problem to sound mixer):

(gdb) bt
#0  0x00007f297504554d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f295e16107e in ?? () from /usr/lib/x86_64-linux-gnu/libasound.so.2
#2  0x00007f295e165fb8 in ?? () from /usr/lib/x86_64-linux-gnu/libasound.so.2
#3  0x00007f295e1a60c8 in ?? () from /usr/lib/x86_64-linux-gnu/libasound.so.2
#4  0x00007f29748c9fc5 in ALSA_PlayAudio (this=0x5633de70d990) at ./src/audio/alsa/SDL_alsa_audio.c:321
#5  0x00007f297489ed90 in SDL_RunAudio (audiop=audiop@entry=0x5633de70d990) at ./src/audio/SDL_audio.c:215
#6  0x00007f29748a6f58 in SDL_RunThread (data=0x5633de686360) at ./src/thread/SDL_thread.c:204
#7  0x00007f29748e79d9 in RunThread (data=<optimized out>) at ./src/thread/pthread/SDL_systhread.c:47
#8  0x00007f2975e5a424 in start_thread (arg=0x7f295622e700) at pthread_create.c:333
#9  0x00007f297504e9bf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105

Python version: 3.5.3
libasound2 version: 1.1.3-4 (Debian testing)

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• Bitbucket: https://bitbucket.org/pygame/pygame/issue/331

[illume]

Original comment by Thomas Kluyver (Bitbucket: takluyver, GitHub: takluyver):

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I can reproduce this if I install from a wheel from PyPI, but not if I install pygame from source. That points to some error with the packaging - maybe an issue with the old ALSA library that it's built with. Possibly we need to try building a newer version of ALSA from source.

[illume]

Original comment by Thomas Kluyver (Bitbucket: takluyver, GitHub: takluyver):

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I was hoping building with a newer version of ALSA (pull request https://bitbucket.org/pygame/pygame/pull-requests/77/build-alsa-lib-ourselves-in-docker-base/diff) would fix this, but it does not seem to, unfortunately. I'm not sure what else to try.

[astronerdnj]

Hi there,

I have exactly the same problem running Pygame 1.9.3 with Python 3.5.2 under Ubuntu 1.6.04 LTS. All I have to do is pygame.init() and the CPU utilization shoots up drastically. I tried following this with pygame.mixer.quit() but it made no difference. I believe I installed Python using PIP3.

Just wondering if you have made any progress on the issue and/or have any ideas on what I should do?

Thanks

[takluyver]

I think you can work round it by building pygame yourself from source. I haven't made any progress in working out what the problem is.

[davidshumway]

Noticing this behavior as well: Roland00111/Trumpocalypse#18.

[steckelj]

I also have this behavior on a pi, however the pygame.mixer.quit() does not resolve the problem. Does anyone have a good link on building from source on raspbian?

[davidshumway]

@steckelj One solution was maybe to not use pygame.init(). Are you using this? If so, try not doing so. Instead, do pygame.___.init() for any modules that are required. Such as pygame.display.init() and pygame.mixer.init() and pygame.font.init(). If you are interested see https://github.com/Roland00111/Trumpocalypse/blob/master/UI/Trumpocalypse.py for implementation.

[steckelj]

I am actually only using pygame.display.init(). I read many guides on the high CPU utilization before I posted on the issue here, and I have no loop and am just sitting at pygame.event.wait() with no allowed events and have near 100% CPU. No other updating. Is it possible I'm not experiencing the same issue?

I'll have to try a test pygame.display.init() only and see if I get the same thing.

I did find what looks to be good instructions for building from source, see pygame section here: http://elinux.org/RPi_Debian_Python3
(I have yet to test the instructions)

[davidshumway]

Okay. Yes, for us it was similar. One solution was to use pygame.time.wait(0) in the while loop. See here: https://github.com/Roland00111/Trumpocalypse/blob/master/UI/eventsloop.py.

        while event_loop:
            self.process_pygame_events()
            pygame.time.wait(0)

Where process_pygame_events() is a function where pygame.event.get() is looped through.

Another solution may be related to clock tick() or fps.