1236437 - Leaving Firefox running during a long time exhausts all my file descriptors

Status: NEW

(Core :: Networking, defect, P3)

Description

[Julien Wajsberg [:julienw]]

I left my Firefox instances open during my 2-week holiday.

When I came back, I found that nothing was working on my computer. After some debugging I found that the file descriptor space was exhausted.

A quick look at `lsof` showed me that all Firefox instances were exhausting the space.

My aurora instance (the main one, with some hundreds tabs open, e10s with processCount set to 8) had 30K+ open fds. That's for the main process only.
Moreover its Web subprocesses also had between 5K and 11K additional open fds.
So this only instance had 93838 open fds.

So we could say that I shouldn't have changed "dom.ipc.processCount".

However my separate nightly instance I use as Gaia test runner (not e10s) had 15K+ open fds.

Comment 1

[Julien Wajsberg [:julienw]]

Attachment: lsof output

Pid 11379 is my not-e10s nightly instance.
All other pids are from my e10s aurora instance.

Comment 2

[Firefox Bug Husbandry Bot]

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258

Comment 3

[Firefox Bug Husbandry Bot]

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258

Comment 4

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

I found this bug while entering a new bug that happens to have similar keywords.

The lsof output appears to list each thread separately, which is going to massively inflate any count of anything over the real value.  Also, the lines with "mem" or "DEL" or anything that doesn't start with a number in the "FD" column aren't file descriptors; they're memory mappings (or other non-fd references, like cwd and rtd), and they don't count against fd limits.

Filtering all that out, it looks about the same as what I see locally in the present day: the parent process has 200-300 fds open, and each child process has a few dozen.  Nothing that should run an entire system out of fds in any case — the total number of fds in the attached file is 640.