Memory leak when opening images about pillow

[Yay295]

It looks like it thinks the errors might be coming from lines 192 and 700?

Pillow/src/PIL/PngImagePlugin.py

Lines 188 to 192 in 955c5da

	def call(self, cid, pos, length):
	"""Call the appropriate chunk handler"""
	logger.debug("STREAM %r %s %s", cid, pos, length)
	return getattr(self, "chunk_" + cid.decode("ascii"))(pos, length)

Pillow/src/PIL/PngImagePlugin.py

Lines 700 to 702 in 955c5da

	class PngImageFile(ImageFile.ImageFile):
	format = "PNG"
	format_description = "Portable network graphics"

[radarhere]

If I increase the number of loops to 1000, I find that the memory drops down again at a certain point. Since it is not continuously increasing, I don't think it is a leak.

You might like to read #7935, in particular #7935 (comment)

Pillow's memory allocator doesn't necessarily release the memory in the pool back as soon as an image is destroyed, as it uses that memory pool for future allocations. See Storage.c (https://github.com/python-pillow/Pillow/blob/main/src/libImaging/Storage.c#L310) for the implementation.

[Yay295]

If I increase the number of loops to 1000, I find that the memory drops down again at a certain point.

It would probably be good to add gc.collect() (import gc) to the end of each loop. It might just not be running that often.

[radarhere]

It would probably be good to add gc.collect() (import gc) to the end of each loop. It might just not be running that often.

I added gc.collect() in, but it doesn't make an obvious difference.

It looks like it thinks the errors might be coming from lines 192 and 700?

I see line 1083 on my machine. This would be easier to discuss if the original image could be uploaded here.

I have previously encountered an error in Webp formats. The leak was in the WebPImagePlugin plugin. I solved this by changing the value of the variable HAVE_WEBPANIM (PIL._webp.HAVE_WEBPANIM) to False.

If I test a WebP image with your above code, I again find that the memory drops down again at a certain point.