fix(jest-leak-detector): gc() even harder

[FauxFaux]

Summary

jest-leak-detector declares a leak in some of our large projects, a leak which does not exist. I have bisected it down to there being too deep require() trees, and/or too many files loaded.

It is definitely not a timing issue; replacing the extra gc() with a multi-second sleep does not fix it. Calling gc() from the app code surprisingly does fix it, at least, for us. My working theory is that the app's gc() takes out some of the actual garbage, leaving leak-detector's gc() time to actually collect all of the code, resulting, eventually, in no leak.

I realise this is hot garbage. I'm absolutely not going to try and write a test for this, and I understand if you close the PR with nelson.gif, and I will continue running with hacks, or try and raise a PR which allows the leak-detector implementation to be configurable.

Tested on node 12 and 14, same behaviour.

Test plan

I really advise that you don't.

There are tests which cover the leak detector's behaviour, and they are not broken.

[github-actions[bot]]

This PR is stale because it has been open 1 year with no activity. Remove stale label or comment or this will be closed in 30 days.

[FauxFaux]

I suspect this is still useful, given other people have raised it. I haven't tested it against the new leak detector code, with FinalisationRegistry, though.

[SimenB]

If a test can be added that shows that it works properly with more gc calls, I'm happy to merge this 🙂

[github-actions[bot]]

This PR is stale because it has been open 1 year with no activity. Remove stale label or comment or this will be closed in 30 days.

[github-actions[bot]]

This PR was closed because it has been stalled for 30 days with no activity. Please open a new PR if the issue is still relevant, linking to this one.

[SimenB]

FWIW, GC run was made more aggressive in #14526

[github-actions[bot]]

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