timers: do not retain a reference to the async store after firing

[mcollina]

After firing timers, we can clean them up by iterating over all active stores and setting the relevant symbols to undefined.

This is still a draft because we will need to extend it to immediates and intervals, too.

Fixes #53408

[mcollina]

I've opened a draft PR to discuss a possible solution to #53408.

cc @nodejs/diagnostics @nodejs/timers let me know what you think.

[Flarna]

What about moving this function into async_hooks to avoid the need to expose getActiveStores() there?
An alternative would be to use a single object on the resource which holds all stores. This would reduce the number of properties added on resource objects - and avoid the need of a for loop to clear it.

[Qard]

A helper that receives a resource and clears all the store data off it would be better than exposing the stores list as we do now. As it is presently, one could get and retain access to a store in a way unintentional from the perspective of the store owner, which is a bit dangerous from a memory perspective.

[Flarna]

maybe clear also _timerArgs.

[mcollina]

I've updated this PR to address the review feedback:

1. Instead of exposing getActiveStores(), added a clearStores(resource) helper function in async_hooks that takes a resource and clears all store references from it. This avoids exposing the internal stores list.
2. Added cleanup for _timerArgs in addition to _onTimeout and async stores.
3. Extended the cleanup to immediates (setImmediate) and intervals (setInterval) as well.
4. Updated the test to cover all three cases.

cc @Flarna @Qard

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.34%. Comparing base (040c51c) to head (0ad04f6).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #53443   +/-   ##
=======================================
  Coverage   90.34%   90.34%           
=======================================
  Files         732      732           
  Lines      236455   236542   +87     
  Branches    44528    44534    +6     
=======================================
+ Hits       213615   213697   +82     
- Misses      14544    14545    +1     
- Partials     8296     8300    +4     

Files with missing lines	Coverage Δ
lib/async_hooks.js	100.00% <100.00%> (ø)
lib/internal/async_local_storage/async_hooks.js	98.12% <100.00%> (+0.08%)	⬆️
lib/internal/timers.js	99.86% <100.00%> (+0.14%)	⬆️

... and 49 files with indirect coverage changes

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