我是否需要完成一个主题才能被垃圾收集? [英] Do I need to complete a Subject for it to be garbage collected?

问题描述

我在我的 Angular 组件中遵循一个清理模式，如下所示:

I follow a cleanup pattern in my Angular components that looks like this:

class SomeComponent implements OnInit, OnDestroy {
    private destroy$ = new Subject();

    ngOnInit() {
        service.someStream().takeUntil(this.destroy$).subscribe(doSomething);
    }

    ngOnDestroy() {
        this.destroy$.next(true);
    }
}

这样做的好处是可以在组件销毁时自动取消订阅.

This has the benefit of automatically unsubscribing when the component is destroyed.

我的问题是:对 destroy$ 的引用是否会因为我没有调用 this.destroy$.complete() 而无限期地存在，或者它会不会得到 GC'ed 在父类被收集时?

My question is: Does a reference to destroy$ stick around indefinitely because I haven't called this.destroy$.complete(), or will it get GC'ed when the parent class is collected?

推荐答案

如果你查看 Subject.complete，你会找到答案:

If you look at the source for Subject.complete, you'll find the answer:

complete() {
  if (this.closed) {
    throw new ObjectUnsubscribedError();
  }
  this.isStopped = true;
  const { observers } = this;
  const len = observers.length;
  const copy = observers.slice();
  for (let i = 0; i < len; i++) {
    copy[i].complete();
  }
  this.observers.length = 0;
}

调用 complete 通知任何观察者，然后清除观察者数组.除非您有一个引用 Subject 的观察者/订阅者，否则 complete 实现中没有任何内容会影响 Subject> 可能会被垃圾收集.

Calling complete notifies any observers and then clears the array of observers. Unless you have an observer/subscriber that has a reference to the Subject, there is nothing in the complete implementation that would affect whether or not the Subject could be garbage collected.

RxJS 向订阅者推送通知.订阅者不持有对 observable 的引用；正好相反.所以，除非你已经明确地创建了一个持有对 Subject 的引用的订阅者——通过闭包或其他一些机制——没有必要调用 complete 进行垃圾收集目的.

RxJS pushes notifications to subscribers. Subscribers don't hold references to the observables; it's the other way around. So, unless you've explicitly created a subscriber that holds a reference to the Subject - via a closure or some other mechanism - there's no need to call complete for garbage-collection purposes.

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