532902 - Expose information about repeating timers

Status: NEW

(Core :: DOM: Core & HTML, defect, P5)

Description

[Boris Zbarsky [:bzbarsky]]

It might be good to be able to ask Firefox a question like "which web pages are doing repeating timers, and what's the delay on them?"  Specifically, this would list interval timers and timeout timers with a nesting level above a certain depth (say 100).  We could do this by enumerating all the windows and then for each window inspecting its timeout list.

The goal would be to try and understand which web pages might be sucking up CPU while the browser is supposedly idle.

John, would Firebug be interested in this sort of information on a per-window basis?

Comment 1

[Boris Zbarsky [:bzbarsky]]

The comment 0 proposal won't catch a page that repeatedly sets timeouts off an interval timer, necessarily.  We could track the nesting level for intervals too, so said timeouts would get that nesting level.

Comment 2

[John J. Barton]

(In reply to comment #0)
> John, would Firebug be interested in this sort of information on a per-window
> basis?

Yes, Firebug very much wants to know similar information but I'd put the question differently. For a given window (JS program) we want to know all of the setTimeout and setInterval calls pending with the ability to debug them.

If the goal is simply to determine JS execution time however I think we can do that with jsd's topLevelHook.

Comment 3

[Boris Zbarsky [:bzbarsky]]

The goal is to answer the following question: "Which tabs should I close so that my browser stops draining my battery?"

Comment 4

[Boris Zbarsky [:bzbarsky]]

At least that's my goal; I just figured Firebug might be interested in similar information so we might as well gather requirements from you guys when deciding  the API to expose here...

From a web developer's point of view, the question might be "what timers on my page make it slow?"

Comment 5

[Johnny Stenback (:jst)]

I think if we expose a list of timers and/or intervals we should just expose them all, and let the consumer of this API filter out ones that repeat slower than x or what not. Seems like an API worth adding.

Comment 6

[Boris Zbarsky [:bzbarsky]]

Sure, if we expose the repeat and nesting values the consumer could just handle it.

Comment 7

[Boris Zbarsky [:bzbarsky]]

So just hang this off windowutils?

Comment 8

[Johnny Stenback (:jst)]

Yeah, I think that'd be the best place for it.

Comment 9

[Firefox Bug Husbandry Bot]

https://bugzilla.mozilla.org/show_bug.cgi?id=1472046

Move all DOM bugs that haven’t been updated in more than 3 years and has no one currently assigned to P5.

If you have questions, please contact :mdaly.