Firefox pegs CPU usage immediately, even in safe mode

[Mike Hicks]

After updating to Firefox 13.0.1 (13.0.1+build1-0ubuntu0.11.10.1), the browser immediately starts using large amounts of CPU time (50 to 100%), even if I start the browser in "safe mode" with plugins and other features disabled. CPU usage remains consistently high as I browse around to other places.

My home page is "about:startpage", the Ubuntu standard.

This should not happen. CPU usage should be at or near zero upon loading a simple page like that.

[mike@3po][~]$ lsb_release -rd
Description: Ubuntu 11.10
Release: 11.10
[mike@3po][~]$ apt-cache policy firefox
firefox:
  Installed: 13.0.1+build1-0ubuntu0.11.10.1
  Candidate: 13.0.1+build1-0ubuntu0.11.10.1
  Version table:
 *** 13.0.1+build1-0ubuntu0.11.10.1 0
        500 http://us.archive.ubuntu.com/ubuntu/ oneiric-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ oneiric-security/main amd64 Packages
        100 /var/lib/dpkg/status
     7.0.1+build1+nobinonly-0ubuntu2 0
        500 http://us.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Brian Brazil (bbrazil)]

I'd like to confirm this on 12.04 with 13.0.1+build1-0ubuntu0.12.04.1.

I'm seeing the same from chrome too, which is very odd. A reboot seems to have cleared it, leap second maybe?

[Mike Hicks (hick0088)]

Thanks. I was beginning to feel a bit silly after a reboot fixed my issue as well. I had first tried restarting my X environment, thinking that some Gnome libraries or protocols might have gotten out of sync somehow. I rarely reboot my machine since issues can normally be resolved through other means.

[ten (tenpou)]

Big thank you, both of you. I was going crazy trying to find out the cause as I normally reboot only after a kernel update, and that was the last thing on my mind to try it. Fixed for me, too (12.04 / 13.0.1+build1-0ubuntu0.12.04.1).

[Mike Hicks (hick0088)]

Just since I'm not sure I want to file another bug against something that may be in a library function or system call, I'll note here that mythfrontend and mythbackend processes (from MythTV) were also running hot on a machine I use as a DVR. Those processes are more heavily multi-threaded, so they showed well over 100% CPU usage.

[Mike Hicks (hick0088)]

This bad behavior seems to have been caused by issues with futex system calls. Here's the most detailed description I've seen so far, including a small test program that can be used to replicate the behavior (I haven't tried it since it modifies the system time):

https://lwn.net/Articles/504658/

Rather than rebooting, simply setting the system time manually or finding some other way to call settimeofday() would have also restored normal behavior.

[JP Vossen (jp-jpsdomain)]

I had 4 machines affected by this problem, 3x on Ubuntu 10.04 and 1 on 12.04, all with FF 13.0.1. It also seemed like Thunderbird was a problem, though not as bad as FF. Reboots "fixed" them all, but that's very disappointing. Ubuntu/ntp/GNU/Linux should handle time and leap-seconds more gracefully than this... :-( If I wanted to have time problems and have to reboot to fix things, I could run Windows.