1191909 - e10s spinner blocks progress at startup apparently due to overload with many windows/tabs

Status: RESOLVED FIXED

(Core :: DOM: Content Processes, defect)

Description

[Randell Jesup [:jesup] (needinfo me)]

With 27 windows, and ~1700 tabs, it's impossible now to start in e10s mode.  The cause seems to be the spinner changes; xorg is using 100% of a core and after a little while, no progress is seen.  Closing windows down to around 6 finally (after some minutes) starts to get progress slowly, and once content actually loads things go back to normal.

Supposition is that the spinner is chewing the system trying to animate N windows off the vsync driver.

Linux Fedora 21, Xeon/16GB, fresh boot.

Will attach profile of master process

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Attachment: spinner.html

jprof of problem.  Note that 63.6% of CPU used by the Master process was in mozilla::RefreshDriverTimer::Tick() (Note: not wall-clock-time - firefox (master) was using around 15-20% of a core, xorg was using 100% continuously).  That's called from the VSyncRefreshDriver runnable.  Everytime I broke in gdb in the master, it was in XFlush() call from Tick() (updating the spinner).  (Wall-clock jprofs were broken by linux kernel changes a few years ago, forcing on-thread registration)

Comment 2

[Randell Jesup [:jesup] (needinfo me)]

Appears to have regressed (or at least gotten much worse) sometime in the last several weeks; the 'old' spinner didn't seem to cause this (though it may have slowed startup)

Comment 3

[:Felipe Gomes (needinfo for replies!)]

Could you make your own build (and perhaps copy your profile) to test it and compare if removing this opacity here helps?
http://mxr.mozilla.org/mozilla-central/source/browser/base/content/tabbrowser.css?rev=0e66ab5ef1fa#88

Comment 4

[Randell Jesup [:jesup] (needinfo me)]

(In reply to :Felipe Gomes from comment #3)
> Could you make your own build (and perhaps copy your profile) to test it and
> compare if removing this opacity here helps?
> http://mxr.mozilla.org/mozilla-central/source/browser/base/content/
> tabbrowser.css?rev=0e66ab5ef1fa#88

With the opacity commented out, I have no trouble loading that profile.  xorg typically sits around 15-17%, instead of pegged at 100%.  We have a winner!

Comment 5

[:Felipe Gomes (needinfo for replies!)]

Awesome! Thanks. This should be fixed by bug 1193668