1275313 - 100% CPU, unresponsive, with profiler installed but supposedly disabled

Status: RESOLVED WORKSFORME

(Core :: Gecko Profiler, defect)

Description

[Steve Fink [:sfink] [:s:]]

For a while now, I have been getting into a state where the Web Content process is pegged at 100% CPU. The firefox process is a steady 4% or so, even when idle. I can interact with the chrome just fine, but no tabs will load. Opening a new tab and navigating to some URL will immediately pop up the "...slowing down your browser. What would you like to do?" doorhanger (I don't know what the first part is, because with Tree Style Tabs it's underneath my pinned tabs. But something like "This web page".) and it spins on Connecting...

I had the Gecko Profiler enabled when it started happening, and then disabled it via the bottom doorhanger "Gecko Profiler might be making Nightly run slowly." But strace of the content process shows it's still getting constant SIGPROF signals. It is doing a trickle of other system calls too:

% strace -p 6851 |& egrep -v 'SIGPROF|futex|rt_sigreturn'
strace: Process 6851 attached
strace: [ Process PID=6851 runs in x32 mode. ]
strace: [ Process PID=6851 runs in 64 bit mode. ]
madvise(0x7f701af00000, 16777216, MADV_DONTNEED) = 0
madvise(0x7f701bf00000, 33554432, MADV_DONTNEED) = 0
--- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TKILL, si_pid=6851, si_uid=500} ---
mmap(NULL, 134217728, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6f89e00000
madvise(0x7f6f93300000, 67108864, MADV_DONTNEED) = 0
--- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TKILL, si_pid=6851, si_uid=500} ---
getrusage(RUSAGE_SELF, {ru_utime={42506, 477990}, ru_stime={9772, 790242}, ...}) = 0
getrusage(RUSAGE_SELF, {ru_utime={42506, 478570}, ru_stime={9772, 790242}, ...}) = 0
munmap(0x7f6f89e00000, 134217728)       = 0
write(11, "\0", 1)                      = 1
madvise(0x7f7079728000, 524288, MADV_DONTNEED) = 0
madvise(0x7f7003e8c000, 131072, MADV_DONTNEED) = 0
madvise(0x7f6f98200000, 1048576, MADV_DONTNEED) = 0
--- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TKILL, si_pid=6851, si_uid=500} ---
madvise(0x7f6f98300000, 2097152, MADV_DONTNEED) = 0
madvise(0x7f6f98500000, 4194304, MADV_DONTNEED) = 0
madvise(0x7f6f98900000, 8388608, MADV_DONTNEED) = 0
--- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TKILL, si_pid=6851, si_uid=500} ---
madvise(0x7f701af00000, 16777216, MADV_DONTNEED) = 0
--- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TKILL, si_pid=6851, si_uid=500} ---

The chrome process is also getting SIGPROFs. The Web Content process is

home/sfink/Downloads/firefox/plugin-container -greomni /home/sfink/Downloads/firefox/omni.ja -appomni /home/sfink/Downloads/firefox/browser/omni.ja -appdir /home/sfink/Downloads/firefox/browser 6706 true tab

I don't have symbols for this build, and it'd probably be a little tough to get them because it has been upgraded so the original binaries are deleted anyway.

This used to happen to me a few times a day. I haven't seen it much for a while. I am not 100% sure it is related to the profiler. I will restart with the profiler disabled and see what happens.

Comment 1

[Steve Fink [:sfink] [:s:]]

I saw this fairly frequently a while back, during a period I was trying to always run with the profiler on. I ended up disabling it as a result. I *might* have seen it once recently, but I'm not sure. I definitely see firefox burning 20-50% of my CPU for no particular reason at various times, but I can't be sure it has anything to do with the profiler; I've seen that without, too.

Comment 2

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

I haven't seen or heard about such issue recently, so I'll mark this bug WFM. Please reopen if you experience it again.