1312701 - painting is much slower on setImmediate demo than Blink

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect, P3)

Description

[Pierre Ossman]

User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:49.0) Gecko/20100101 Firefox/49.0
Build ID: 20160919122641

Steps to reproduce:

Call window.postMessage() in order to split up a large job and allow the browser to schedule other things in between. See example here:

http://jphpsf.github.io/setImmediate-shim-demo/

This is a very important use case as it is currently the only API that allows splitting up work without throttling it (in contrast with e.g. setTimeout()).


Actual results:

Chrome executes the test in 257 ms, compared to Firefox' 2128 ms on the same system. I.e. it is almost 10x as fast.


Expected results:

The numbers for Chrome and Firefox should at least be of the same magnitude.

Comment 1

[Josh Matthews [:jdm]]

Locally I get ~200ms for Chrome and ~800ms for Firefox nightly.

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Based on profile Gecko spends most of the time in painting (and I assume postMessage just needs to wait for painting to finish), but would need to also verify child process isn't just waiting for something.
Dispatching/handling 'message' event itself takes ~4%.

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

tentatively gfx

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Attachment: a testcase for postMessage only

This testcase takes about 2100ms on Nightly (javascript.options.asyncstack=false), and 2800ms in Chrome. So the issue clearly isn't in postMessage but in whatever is done between the postmessage tasks.

Comment 5

[Ben Kelly [:bkelly, not reviewing]]

Yea, on my machine the performance timeline shows paints taking 15ms to 25ms on FF50.  Chrome does the paints in less than 1ms.

Comment 6

[Pierre Ossman]

I'm seeing about the same numbers in Chrome 54 and Firefox 49 here with that test case. Sorry for assuming that postMessage() was to blame.

Comment 7

[Ben Kelly [:bkelly, not reviewing]]

Note, the page appears to be using CSS transforms to move the boxes around.  So I don't think its not canvas or anything like that.

Comment 8

[Kelsey Gilbert [:jgilbert]]

Async painting?

Comment 9

[Milan Sreckovic [:milan] (needinfo for best results)]

(In reply to Jeff Gilbert [:jgilbert] from comment #8)
> Async painting?

Something like that.

Comment 10

[Guilherme Lima]

It seems this is a lot better now.
I get ~350 ms on Firefox 70 and Nightly 72 and ~250 ms on Chrome 78.

Comment 11

[Mayank Bansal]

Chrome 55ms, Nightly 56ms

Comment 12

[Pierre Ossman]

Getting 144ms with Firefox 102 and 110ms with Chrome 103. In the same ballpark, I guess. :)