[CP] [vm] Fix leakage of file system watcher related data structures

[srawlins]

Commit(s) to merge

3dd9389

Target

stable

Prepared changelist for beta/stable

https://dart-review.googlesource.com/c/sdk/+/311521

Issue Description

Without this fix, there is a bad leak of _Closure objects when using overlapping Directory.watch streams. This change switches a Stream.pipe usage to Stream.listen, and cancels subscriptions.

What is the fix

The fix is to change how these watch events are listened to, and canceling subscriptions.

Why cherry-pick

This memory leak can be very prevalent in the Dart analyzer, and memory usage (including leaks) is a top issue for users of Dart analyzer.

Risk

low

Issue link(s)

#52703

Extra Info

No response

[a-siva]

lgtm

[mraleph]

We might want to cherry pick 8b6e396 as well.

[itsjustkevin]

We might want to cherry pick 8b6e396 as well.

@srawlins should we also be picking the commit @mraleph mentioned above before merging this cherry-pick?

[srawlins]

should we also be picking the commit @mraleph mentioned above before merging this cherry-pick?

8b6e396 was landed recently, so we would want to land this (3dd9389) cherry-pick first. After a quick evaluation, cherry-picking 8b6e396 helps with this memory theme as well.