1420913 - consider notifying PerformanceObserver using idle dispatch

Status: NEW

(Core :: DOM: Performance APIs, enhancement, P3)

Description

[Ben Kelly [:bkelly, not reviewing]]

Apparently the PerformanceObserver spec says that events should be dispatched at low priority during idle times.  No browser does this yet, though.  Chrome is thinking of doing it:

https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/TgoXNRtA3Zs

We should consider it as well.

Valentin, Andrea, what do you think?

Comment 1

[Ben Kelly [:bkelly, not reviewing]]

Note, I think changing this would mainly involve changing this:

https://searchfox.org/mozilla-central/source/dom/performance/Performance.cpp#518

To use NS_IdleDispatchToCurrentThread().

Comment 2

[Valentin Gosu [:valentin] (he/him)]

Andrea has more of an insight into PerformanceObserver behaviour, but this sounds like a reasonable change to me.

Comment 3

[Ben Kelly [:bkelly, not reviewing]]

I think the main concern I have is if sites are depending on the timing somehow.  The blink-dev thread has some discussion of that.

Comment 4

[Andrea Marchesini [:baku]]

(In reply to Ben Kelly [:bkelly] from comment #3)
> I think the main concern I have is if sites are depending on the timing
> somehow.  The blink-dev thread has some discussion of that.

It seems that the discussion is suspended waiting for takeRecords(). We should implement takeRecords() as well, btw. /me filing a bug.