1346608 - FireFox frequently attempts multiprocess browsing, even when multiprocess is disabled

Status: RESOLVED INVALID

(Core :: DOM: Content Processes, defect)

Description

[Tim Hofstetter]

Attachment: Task Manager screenshot showing primary and progeny processes

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Firefox/52.0
Build ID: 20170303022339

Steps to reproduce:

Set browser.tabs.remote.autostart to false in about:config
Set browser.tabs.remote.autostart.2 to false in about:config
Verify that Multiprocess Windows in about:support is disabled

Start browsing with FireFox, watching your Windows Task Manager.



Actual results:

At some entirely arbitrary point outside the control of the user, FireFox opens its own second process. In my case, this stalls the browser and dramatically slows down the rest of the computer until I manually kill either the second process or the browser's main process. The second process is verified to have been spawned by the main browser process.


Expected results:

FireFox should not open any additional processes when multiprocess is disabled.

Comment 1

[YF (Yang)]

It may be a plugin container instead of the e10s processes.


Force disable e10s:
Within about:config create a new boolean pref named browser.tabs.remote.force-enable and set it to false.

Comment 2

[Tim Hofstetter]

Done. No joy, FireFox still spawns a second process at random times. I was skeptical that this step would work, since all my plugins are set to "Ask" and none have "asked" for a very long time now.

Comment 3

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

Your useragent says you are using Windows XP. According to bug 1296279, e10s is disabled on Windows XP. So this should be a plugin process.

Can you get the arguments for the second process, e.g. by inspecting the Properties of the second Firefox process? If yes, please post them here.

Comment 4

[Tim Hofstetter]

Here we go:

"C:\Program Files\Mozilla Firefox 8.0.1\firefox.exe" -contentproc --channel="3616.15.1381727796\612217977" -greomni "C:\Program Files\Mozilla Firefox 8.0.1\omni.ja" -appomni "C:\Program Files\Mozilla Firefox 8.0.1\browser\omni.ja" -appdir "C:\Program Files\Mozilla Firefox 8.0.1\browser"  3616 "\\.\pipe\gecko-crash-server-pipe.3616" tab

Comment 5

[Tim Hofstetter]

More (new) information: I've now written a Jäger application that hunts down and kills secondary FireFox processes as soon as they appear, and as a byproduct I've discovered that FireFox refuses to open local (on my own hard drive) HTML files without first opening a second process. After the local file has been opened, it's fine to kill the second process because the second appears to hand off the file to the primary FireFox. Bizarre behavior, and a real PITA for a developer like me, but maybe a valuable clue to whomever looks at this BugZilla.

Comment 6

[Emil Pasca [:emilpasca]]

Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Firefox/52.0

I have tested this issue on Windows XP x32 with Firefox (52.0) and haven't managed to reproduce the issue.
When opening the browser, in the Windows Task Manager, only one instance of Firefox process is being displayed.
Sebastian, can you please take a look in comment 4, maybe is something that explains this?

Comment 7

[Emil Pasca [:emilpasca]]

Tim, can you please retest this using a new clean Firefox profile, maybe even safe mode, to eliminate custom settings as a possible cause (https://goo.gl/AR5o9d).

Comment 8

[Tim Hofstetter]

Moments ago I created a brand-new empty profile and used it to start FireFox. Within five minutes, FireFox had launched five new child processes (each of which was immediately killed by my Jäger application) on my machine. Oddly, it also suddenly refused to let me open any individual emails in my GMail account (although Chrome opens them just fine). Irony: I had to use Chrome to get to my email notification of this NeedInfo so I could respond to it.

I also notice that in this new profile, FireFox is using between 40% and 99% of my CPU just tracking the mouse, doing nothing else. That CPU usage drops to ~2% when I alt-tab away to anything else, or when I move the mouse pointer up to the title bar.

I have no bookmarks in this account. I have three open tabs: Yahoo mail (legacy), GMail, and FaceBook. I have zero enable extensions and only one enabled plugin: the Cisco OpenH264 codec installed by Mozilla. All other plugins are set to "Ask". I have no service addons.

Comment 9

[Tim Hofstetter]

Addendum: I'm currently (as of last night) testing with FireFox 50.0.2.

Comment 10

[Tim Hofstetter]

Addendum #2: If it makes a difference, my on-motherboard GPU doesn't support OpenGL.

Comment 11

[Tim Hofstetter]

Addendum: The problem persists when I start FireFox in Safe Mode and use the new profile.

In fact, the new profile actually starts new child processes MORE OFTEN than my old well-worn profile does. In the old profile, new spawns have calmed down to only a few per day. One or two FF updates ago, I was getting as many as a dozen per hour.

Comment 12

[Emil Pasca [:emilpasca]]

Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Firefox/52.0

I've retested this issue on Windows XP x32, with Firefox release 52.0 and the latest Firefox release 52.0.2 and managed to reproduce it.
With a new profile having the following prefs, browser.tabs.remote.autostart and browser.tabs.remote.autostart.2, set to "false" when navigating to facebook.com, you can observe that there are two "firefox" processes active in the Windows Task Manager.

Comment 13

[Andrew McCreight [:mccr8]]

The thumbnail service (used to generate screenshots for the new tab page) uses a separate content process when e10s is disabled. Maybe that is what you are seeing.

Comment 14

[Denis]

I am observing similar behavior with Firefox 56 beta 11 on Windows 7. And in my case it is caused by Screenshots extension (https://screenshots.firefox.com/#hello). When I disable it through "extensions.screenshots.disabled" second (tab) process is closing.

Comment 15

[Jim Mathies [:jimm]]

This is the thumbnail service.

Comment 16

[Tim Hofstetter]

@Jim Mathies: I beg your pardon? Invalid Resolved? The problem still exists, and it happens with a totally clean FireFox and a brand-new empty profile. It happens on my machine dozens of times per day (FireFox has only run on this machine for about 45 minutes today, and it's already happened twenty-one times). The problem seems to be getting worse; it's gotten so bad that I only start FireFox when I absolutely need to, so bad that Chrome and Opera are looking more attractive every day.

Testing the new-tab thumbnail service: yep, that appears to be where the problem lies. I open a new tab, the thumbnails pop up, THEN six (SIX, 6) new processes appear & are killed by my Jäger process. Not nine processes (there are nine thumbnails in that view), but SIX processes.

So... how do we go about fixing this issue with FireFox starting six new CPU-hogging processes every time I open a new tab? Can I disable the new tab thumbnail thing in hopes that doing so might work?