Memory leak in tests with zone.js >= 0.9.0

[belchevgb]

🐞 bug report

Affected Package

The issue is caused by package:

zone.js: 0.9.0

Is this a regression?

Yes. The tests didn't cause Chrome to crash.

Description

When I've upgraded zone.js from 0.8.26 to 0.9.0 or higher, this problem appeared. I have 3000 unit/integration tests. We use heavily dynamic component creation. Our tests currently cannot be executed at once, because zone.js(the timers patch) keeps a reference to tasks created from setTimeout() in tasksByHandleId in the patch method. When I call clearTimeout() in ngOnDestroy() I can see that the task is not removed from tasksByHandleId because it's status is notScheduled.

🔬 Minimal Reproduction

https://github.com/belchevgb/zonejs-memory-leak

🌍 Your Environment

Angular Version:

Angular CLI: 11.0.6
Node: 14.3.0
OS: win32 x64

Angular: 11.0.7
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router
Ivy Workspace: Yes

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1100.6
@angular-devkit/build-angular   0.1100.6
@angular-devkit/core            11.0.6
@angular-devkit/schematics      11.0.6
@angular/cli                    11.0.6
@schematics/angular             11.0.6
@schematics/update              0.1100.6
rxjs                            6.6.3
typescript                      4.0.5
zone.js                         0.10.2

Anything else relevant?
SNAPSHOT

[belchevgb]

Any info if this will be resolved in some minor version or in v12?

[JiaLiPassion]

@belchevgb , I will check this one, thanks!

[JiaLiPassion]

@belchevgb , I am not quite understand your reproduce logic,

ngAfterViewInit(): void {
    this.timeoutId = setTimeout(() => {
      // do some work
    });
  }

  ngOnDestroy(): void {
    clearTimeout(this.timeoutId);
  }

the setTimeout in ngAfterViewInit has been invoked after 0ms, and in ngDestroy, clearTimeout will do nothing since the timeout is already done.

So could you create reproduce repo to show the issue?

[belchevgb]

The problem is that when you call setTimeout in afterViewInit this async task gets scheduled and the task is stored in tasksByHandleId. When we call ngOnDestroy and clearSetTimeout, this tries to remove the given task from tasksByHandleId cache, but it is with status "not scheduled", so this task never gets removed.

[belchevgb]

Here is the repro repo https://github.com/belchevgb/zonejs-memory-leak

[JiaLiPassion]

@belchevgb , I can reproduce now, thanks for reporting this issue, I will create a PR to fix it asap.