1403884 - Netmonitor causing long BHR hangs

Status: NEW

(DevTools :: Netmonitor, defect, P3)

Description

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

Attachment: netmonitor_hangs.png

I'm looking at http://arewesmoothyet.com.
I don't know how to share links to that, so here is a screenshot.

Comment 1

[Alexandre Poirot [:ochameau]]

It looks like bug 1404917 finally fixed the very long hangs, over 1s.

https://arewesmoothyet.com/?mode=track&trackedStat=Devtools%20Hangs
(you have to click on thresholds label <1s to really see that the slowest hangs are very rare)

But some work is still pending in bug 1404913, which should continue removing hangs related to netmonitor.

Keeping open to still track the other smaller hangs.

Comment 2

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

Just looked at the data and netmonitor is still there.

Comment 3

[Alexandre Poirot [:ochameau]]

Bug 1404913 only had an impact on hangs >=1s.
I'm a bit surprised, I thought it would lead to a much more important improvement.
We used to copy all requests response content. Always, for all requests, no matter if we actually opened the response content panel. We no longer do that since bug 1404917 landed.
It looks like BHR hangs aren't necessarely reflecting all slownesses equally. It seems like slow reflows have a very big impact on the number of BHR hangs being reported. I understood that while writing Q4 report [1].
A very naive fix on the console (bug 1400176) reduced the number of hangs associated to the console by 2x or 4x!
I'm currently investigating slow reflows related to netmonitor in bug 1425978.

[1] https://docs.google.com/document/d/e/2PACX-1vQ3ZxZR8muRVND9ghZD8myEYRR0k2IEg7Md_cC4r9G8WXtUoTkbzOuz-ZD-U3VwxWSnyzRt0MmvhL_G/pub

Comment 4

[:Harald Kirschner :digitarald]

Network panel is now (just) 0.05% of all BHR hangs in Nightly: http://queze.net/bhr/#filter=netmonitor – all top hangs are styling and reflow

Comment 5

[Florian Quèze [:florian]]

(In reply to :Harald Kirschner :digitarald from comment #4)

Network panel is now (just) 0.05% of all BHR hangs in Nightly: http://queze.net/bhr/#filter=netmonitor – all top hangs are styling and reflow

It's 1.05% for the 20201103 nightly.