`Resampler` object still occupies memory after deletion about pyav HOT 6 OPEN

This is because av.audio.resampler.AudioResampler uses av.filter.graph.Graph, and obviously graphs require a circular reference which would create an object that is not deletable by traversing acyclic reference graphs. Because of it, while the AudioResampler gets deallocated when it gets out of scope, Graph does not.

It is not a bug, because it does not affect the program's correctness, and the author has relied on cpython's implementation of the cyclic garbage collector to clean up the resources. It would be a performance enhancement if the reference loop is eliminated.

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@MahmoudAshraf97, please test again using 851ff21. It will not solve the issue completely, but it could reduce some of the memory footprint.

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This is the result:

I guess the problem still exists, and since repeating the same experiment many times doesn't guarantee exact reproduction, I cant verify whether this is partially solved or not

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Using large enough iteration will help to make the result somewhat deterministic.

In my machine (arm64 M2 Pro Darwin 14.4.1), with delete=False, collect=False, n=200;

Without applying the patch (left) I can see the gc periodically cleans the circular referenced objects and there seems to be some objects that cannot be recovered by gc.

After applying the patch (right) the memory graph is steadily increasing and no signs of visible gc activity. The graph could indicate a real leak though I haven't investigated it further. Overall the memory footprint seems to be significantly smaller.

@MahmoudAshraf97, can you try my patch again with delete=False, collect=False, n=200 and compare it with v12.1.0 or main?

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@moonsikpark The Graph object probably has a memory leak, and it certainly has it's own circular references.

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