live maps at weather.com are slow (with profile)

NEW
Unassigned

Status

()

defect
P3
normal
Last year
Last year

People

(Reporter: asa, Unassigned)

Tracking

Firefox Tracking Flags

(Not tracked)

Details

A user reported extremely slow live maps at weather.com on Firefox 58 and 59. He's got a powerful system (win 10 with an AMD Threadripper 1950x and 64gb of ddr4 3200 driving a 4K display) and this is his profile. https://t.co/ExkAi5nPVF for https://weather.com/weather/radar/interactive/l/USOH1375:1:US?layer=radar&overlays=currtrafficspeed
There are a few things going wrong here at first glance, but the big one appears to involve Stylo / Rayon:

https://perfht.ml/2r25HBM

Content Process 5 (which is hosting at least one weather.com tab) is going absolutely bonkers. Hey emilio, got any insight?
Component: General → CSS Parsing and Computation
Flags: needinfo?(mconley) → needinfo?(emilio)
So, my profile of that page looks fairly different, fwiw, mostly spent in JS.

  https://perf-html.io/from-addon/calltree/?range=19.5583_21.8275&thread=2&threadOrder=0-2-1&v=3

That machine has 16 physical CPUs, which means that we probably choose too many threads for the thread-pool. It's kinda fishy that in that profile there are no restyle markers, but the profile is 1 month old.

Seeing what's going on in the StyleThreads would be useful, but I suspect it's just Rayon scaling not-so-well, and the threads starving and consuming CPU.

Bobby, we had a bug on file for Bas's machine (can't find it). Should we just clamp the number of style threads?
Flags: needinfo?(emilio) → needinfo?(bobbyholley)
That discussion was bug 1431285 comment 13. Still on my todo list, but haven't gotten to it, and likely won't get to it before heading out on PTO.

I do think we should probably clamp, but I'd like us to measure per the aforementioned comment.

I'd also like to understand that user's profile better. Could we get her/him to add StyleThread to the list of profiled threads?
Flags: needinfo?(bobbyholley)
Asa, any chance? Thanks!
Flags: needinfo?(asa)
(In reply to Emilio Cobos Álvarez [:emilio] (Away-ish from 27/04 to 09/05) from comment #5)
> Asa, any chance? Thanks!

I'm sorry. I lost track of the reporter. I'll try to find him.
Flags: needinfo?(asa)
(In reply to Asa Dotzler [:asa] from comment #6)
> (In reply to Emilio Cobos Álvarez [:emilio] (Away-ish from 27/04 to 09/05)
> from comment #5)
> > Asa, any chance? Thanks!
> 
> I'm sorry. I lost track of the reporter. I'll try to find him.

Found him and asked for a new profile with StyleThread added. https://twitter.com/asadotzler/status/992309975698427904 for future reference.
Priority: -- → P3
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