Segfault in example aliens script if ran in loop

[ghost]

Environment:

You can get some of this info from the text that pops up in the console when you run a pygame program.

• Operating system (e.g. Windows, Linux(Debian), Linux(Ubuntu), Mac): MacOS 11.2.3
• Python version (e.g. 3.7.9, 3.8.5) : 3.9.2
• SDL version (e.g. SDL 2.0.12): 2.0.14
• PyGame version (e.g. 2.0.0.dev10, 1.9.6): 2.0.1
• Relevant hardware (e.g. if reporting a bug about a controller, tell us the brand & name of it):

Current behavior:

After ~5 minutes of playing, python will give
zsh: segmentation fault python3 -m pygame.examples.aliens

Expected behavior:

The game does not segfault

Screenshots

If applicable, copy and paste screenshots to help explain your problem.

Steps to reproduce:

1. Download pygame
2. Apply the change from https://github.com/pygame/pygame/compare/main...Pycryptor10:patch-1.diff
3. run python3 -m pygame.examples.aliens
4. Keep playing for ~5 minutes

Test code

https://github.com/pygame/pygame/compare/main...Pycryptor10:patch-1.diff

Stack trace/error output/other error logs
See files attached to https://bugs.python.org/issue43671 as I thought it could be a python issue first

[ghost]

Call to __init__ on line 142 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/examples/aliens.py from line 384 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/examples/aliens.py
Call to __init__ on line 112 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 143 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/examples/aliens.py
Call to add on line 117 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 115 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add on line 117 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 133 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add_internal on line 373 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 130 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add_internal on line 153 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 131 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add_internal on line 373 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 130 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add_internal on line 153 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 131 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add_internal on line 1351 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 130 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
zsh: segmentation fault  python3 -m pygame.examples.aliens

is last part executed pre crash

[ghost]

Call to __init__ on line 218 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/examples/aliens.py from line 389 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/examples/aliens.py
Call to __init__ on line 112 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 219 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/examples/aliens.py
Call to add on line 117 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 115 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
Call to add on line 117 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py from line 133 of /Users/cern/vevns/epq2/lib/python3.9/site-packages/pygame/sprite.py
zsh: segmentation fault  python3 -m pygame.examples.aliens

another

[ghost]

I did some more testing and replaced https://github.com/Pycryptor10/pygame/blob/patch-1/src_py/sprite.py#L117-L133 with

def add(self, *groups):
        """add the sprite to groups

        Sprite.add(*groups): return None

        Any number of Group instances can be passed as arguments. The
        Sprite will be added to the Groups it is not already a member of.

        """
        print("call to line 117, reached 126")
        has = self.__g.__contains__
        print("dumping has")
        for attr in dir(has):
            print("obj.%s = %r" % (attr, getattr(has, attr)))
        print("dumped")
        for group in groups:
            if hasattr(group, '_spritegroup'):
                if not has(group):
                    group.add_internal(self)
                    self.add_internal(group)
            else:
                self.add(*group)

but I never saw it get past: print("call to line 117, reached 126") when that was been ran. (It did on my next run when I added code to dump self.__g but I'm not really sure now what to do).

[ghost]

As far as I can confidently see is that the segfault happens within https://github.com/pygame/pygame/blob/main/src_py/sprite.py#L117-L133. Not sure beyond that.

[ghost]

aliens.py(393):         for alien in pg.sprite.spritecollide(player, aliens, 1):
 --- modulename: sprite, funcname: spritecollide
sprite.py(1655):     default_sprite_collide_func = sprite.rect.colliderect
sprite.py(1657):     if dokill:
sprite.py(1659):         crashed = []
sprite.py(1660):         append = crashed.append
sprite.py(1662):         for group_sprite in group.sprites():
 --- modulename: sprite, funcname: sprites
sprite.py(381):         return list(self.spritedict)
Fatal Python error: Segmentation fault

is last thing given when running python with --trace

That matches to https://github.com/pygame/pygame/blob/main/src_py/sprite.py#L371 because of my debug code

[Starbuck5]

If REW1L is correct about the cause of this issue, which I am inclined to think they are, this is not a mac specific issue, and can be reproduced with

import pygame
import gc
 
pygame.font.init()
font = pygame.font.Font(None, 20)
pygame.font.quit()
pygame.font.init()
del font
gc.collect()
print('hey') # never reached

[ankith26]

I cannot seem to reproduce this segfault in the latest version which has the font segfault fix PR merged, so this issue is fixed by that as well (please re-open if you can still reproduce this :) )