1944669 - Warning "failed to send SIGKILL to process" appears in terminal

Status: RESOLVED FIXED

(Core :: IPC, defect, P2)

Description

[Viktor Jägersküpper]

Steps to reproduce on Linux:

• launch Firefox from terminal
• visit www.youtube.com or www.reddit.com (I could reproduce this easier with Youtube, other sites might also work.)
• open new tab
• close tab with Youtube/Reddit
• notice a warning like this in the terminal appearing after a few seconds:
  [Parent 121553, IPC I/O Parent] WARNING: failed to send SIGKILL to process 133325: file /builds/worker/checkouts/gecko/ipc/chromium/src/chrome/common/process_watcher_posix_sigchld.cc:159
• if the warning doesn't appear, try again

I couldn't figure out why the warning doesn't always appear. Interestingly I also got the warning by just visiting Youtube and waiting for some time.

During my regular browsing sessions this warning appears several times. I don't know if this means there is a bug or if this warning should be silenced.

I ran mozregression with --process-output=stdout and got:
Last good revision: 16b2437248d92c7a4d79b5f7ddee09935685e6a6
First bad revision: e3c3c980538708e0cde56b28ffa4e37861640a6d
Pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=16b2437248d92c7a4d79b5f7ddee09935685e6a6&tochange=e3c3c980538708e0cde56b28ffa4e37861640a6d

This points to bug 1658072.

OS: Arch Linux
KDE Plasma 6.2.5 on Wayland

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Setting Regressed by field after analyzing regression range found by mozregression in comment #0.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

:jld, since you are the author of the regressor, bug 1658072, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The bug has a release status flag that shows some version of Firefox is affected, thus it will be considered confirmed.

Comment 4

[Gian-Carlo Pascutto [:gcp]]

I'm going to assume the warning is harmless, but jld can elaborate.

Comment 5

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

As far as I can tell, bug 1658072 didn't change the behavior except for the logging. I have a patch.

Comment 6

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

Attachment: Bug 1944669 - Suppress ProcessWatcher logspam introduced in earlier rewrite.

The case in question is where the process exits before the timeout
expires and it's a forkserver child. Previously (before bug 1658072)
there wouldn't be a log message in this case, but otherwise the effect
was the same: if a process with the given pid was still running, it
would be sent SIGKILL.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3e357dbb1efc
Suppress ProcessWatcher logspam introduced in earlier rewrite. r=ipc-reviewers,mccr8

Comment 8

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/3e357dbb1efc

Comment 9

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:jld, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox136 to wontfix.

For more information, please visit BugBot documentation.

Comment 10

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

Attachment: Bug 1944669 - Suppress ProcessWatcher logspam introduced in earlier rewrite.

The case in question is where the process exits before the timeout
expires and it's a forkserver child. Previously (before bug 1658072)
there wouldn't be a log message in this case, but otherwise the effect
was the same: if a process with the given pid was still running, it
would be sent SIGKILL.

Original Revision: https://phabricator.services.mozilla.com/D237857

Comment 11

[Phabricator Automation]

beta Uplift Approval Request

• User impact if declined: scary-looking log messages that may result in filing unnecessary bugs
• Code covered by automated testing: yes
• Fix verified in Nightly: yes
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: n/a
• Risk associated with taking this patch: very low
• Explanation of risk level: affects only a log message, and only a feature that's usually preffed off
• String changes made/needed: none
• Is Android affected?: no

Comment 12

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/36d11ffea4ef