Symfony version(s) affected

symfony/framework-bundle:
5.3.10, 5.2.14, 5.1.11, 5.4.x-dev@24649c622776b36158f80b81b9455987b8129793 , 6.0.x-dev@5284b7f8419f9ed224d8d00d6c945d566343cd83, 4.4.31, and I assume every version in between.

PHP: 7.4.15, 8.0.11, 8.0.12, PHP 8.1.0RC5

Description

When using the Symfony cache in a certain way (e.g. calling the cache within a closure that is resolving another cache value), there is a memory leak.

It's quite a strange bug and I don't know what is causing it. I was able to reproduce it (more info in the reproducer's readme). I'm not sure if this could be a PHP bug either.

In the reproducer the memory increase is not that high. However, in our own application the memory increase is ~10 MB per call to the method that does a bunch of caching. This is especially a problem in our message consumers.

I'll test the reproducer against some other Symfony versions too.

How to reproduce

Reproducer: https://github.com/Jeroeny/reproduce/tree/cache

Possible Solution

In our own application gc_collect_cycles() mitigated the problem. But not in the reproducer.