computed is no longer controlled by effectScope

[yangmingshan]

Vue version

3.5.4

Link to minimal reproduction

https://play.vuejs.org/#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

Steps to reproduce

1. Change the input value, see if length change.
2. Click the stop button.
3. Change the input value again, see if length change.

What is expected?

The stop button can stop computed in v3.4.38

What is actually happening?

The stop button can not stop computed in v3.5.4

System Info

No response

Any additional comments?

New api added in v3.5 like scope.pause scope.resume have same issue. This use case is made up by me, it's not real. But I don't know if anyone uses like this.

[edison1105]

computed no longer uses effect since v3.5

core/packages/reactivity/src/computed.ts

Lines 22 to 25 in e596378

	* @deprecated computed no longer uses effect
	*/
	effect: ComputedRefImpl
	}

[Shyam-Chen]

I think I will use ref along with either watch or watchEffect.

[MuTsunTsai]

Just happen to notice this issue and my project is affected by this as well. I need computed to pause reactivity if the scope is not "active" (like, when the corresponding workspace is not focused), in order to improve performance.

[ryanlin1986]

My request is to dispose(stop forever, not pause) computed while I don't need it.

[yyx990803]

This is somewhat intentional because computed in 3.5 no longer needs to be explicitly stopped. In 3.5, a computed is automatically de-referenced from all its deps when it loses all subscribers (effects or other computeds) so they can be garbage collected.

@MuTsunTsai I don't think computed needs to be "paused" because they are already lazy (i.e. dep changes only marks a computed dirty, but the actual computation only happens when its value is read).

Imagine an effect using a computed and is paused, and one of that computed's deps change:

• The effect doesn't run because it's paused
• Because it doesn't run, it doesn't read the computed's value
• The computed's getter doesn't run

So pausing the owner effect effectively avoids the computed cost as well.

Closing unless there is a real cases where this is needed.

[MuTsunTsai]

@yyx990803 OK that makes sense, thanks for the clarification.