How do I send signal to all processes in a cgroup?

Asked Apr 08 '21 at 15:07

Active Apr 08 '21 at 15:07

Viewed 1,173 times

kill $(< /sys/fs/cgroup/freezer/<name>/tasks ) works, but looks clumsy, produces a warning if cgroup is empty and may hit command line length limit.

pkill -F does not accept cgroup tasks file as a valid pidfile.

There seems to be no dedicated tool like cgkill.

What should I use (apart from a fully fledged containers like LXC) to make forced cgroup termination more reliable and self-documenting? Ideally it should also do the { SIGTERM, then wait, then freeze, then SIGKILL, then thaw } routine.

asked Apr 08 '21 at 15:07

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Sounds like a fun open source task - add a new flag to `kill` or fix `pkill`... – Aaron D. Marasco Apr 08 '21 at 15:54
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`kill $(< /sys/fs/cgroup/freezer//tasks ) ` has a race condition: new processes may be created in the cgroup between the time you enumerate PIDs and the time you kill them. – Gilles 'SO- stop being evil' Apr 08 '21 at 16:04
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https://news.ycombinator.com/item?id=20599575 suggests that there's no reliable way to avoid the race condition (freezing the cgroup can freeze processes in an unkillable state) until cgroupv2. – Gilles 'SO- stop being evil' Apr 08 '21 at 16:06

How do I send signal to all processes in a cgroup?

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