src: force gc for flaky (deadlock) tests

[jakecastelli]

This patch adds a new flag force_gc_for_test (internal use for test purpose only) to force GC for flaky tests that suffer from deadlock. Refs: #54918 and #56827 (comment)

The deadlock occurs when (correct me if I am wrong):

1. Main thread calls DrainTasks and executes worker tasks
2. Worker task needs memory allocation requiring GC
3. GC must run on main thread, but main thread is busy running the worker task

Notes:

1. v8 RequestGarbageCollectionForTesting will require --expose-gc flag to work which means for the flaky tests that suffer from deadlock we will need // Flags: --expose-gc --force-gc-for-test at the top of the test file.
2. This patch does not resolve the deadlock issue but rather an attempt to reduce the flaky tests without marking them as flaky.
3. Based on the findings, I will take time looking into how chromium handles it and see if we can properly fix it in node, but any help would be greatly appreciated 🙏
4. Bad at naming, if this patch is acceptable, please suggest a good name for the option name.

[nodejs-github-bot]

Review requested:

• @nodejs/config

[lpinca]

v8 RequestGarbageCollectionForTesting will require --expose-gc flag to work which means for the flaky tests that suffer from deadlock we will need // Flags: --expose-gc --force-gc-for-test at the top of the test file.

If we need to update tests one by one we don't need a new flag. We can just call globalThis.gc({ type: 'major' }) when the test is done.

[lpinca]

I also fear that if we did this for all tests we would end up ignoring the underlying issue because it would no longer be a problem. So far only a handful of people have investigated the issue and apparently it is not trivial (#56827). When we no longer have a constant reminder that it exists via CI, it will be forgotten.

[jakecastelli]

Fair points, I will continue to dig the underlining issue with the rest of us, and hopefully we can get it properly fixed.