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-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1958284 Title: shutdown hangs at "Waiting for process: ..." for 90s, ignoring DefaultTimeoutStopSec Status in systemd package in Ubuntu: Fix Released Status in systemd source package in Focal: Fix Released Bug description: [Impact] The systemd shutdown sequence does not honor systemd-system.conf settings when waiting for remaining processes. This means that, for example, if a systemd service specifies KillMode=process and a process remaining from that service does not properly handle SIGTERM, then the remaining process will not be killed until after the compiled-in default value of DefaultTimeoutStopSec (90s), even if the user has changed the setting of DefaultTimeoutStopSec. In such cases, this impacts users by significantly increasing the time required for shutdown/reboot. [Test Plan] * Create a new script, /usr/local/bin/loop-ignore-sigterm: ``` #!/bin/bash loop_forever() { while true; do sleep 1; done } ( trap 'echo Ignoring SIGTERM...' SIGTERM loop_forever ) loop_forever ``` This script will spawn a subshell which will loop forever and ignore SIGTERM. This will force systemd to wait for the subprocess at reboot/shutdown, and eventually send SIGKILL after TimeoutStopSec (DefaultTimeoutStopSec in this case). * Make the script executable: $ chmod +x /usr/local/bin/loop-ignore-sigterm * Create a systemd service for this script. Add the following to /etc/systemd/system/loop-ignore-sigterm.service: ``` [Service] KillMode=process ExecStart=/usr/local/bin/loop-ignore-sigterm ``` * Start the service: $ systemctl start loop-ignore-sigterm.service * Edit /etc/systemd/system.conf, and uncomment the 'DefaultTimeoutStopSec=90s' line. Modify 90s to something much shorter, e.g. 20s. * Re-exec the daemon so this new default takes effect: $ systemctl daemon-reexec * Reboot, and monitor the logs. Observe that systemd-shutdown will wait for the loop-ignore-sigterm process for 90s, instead of the 20s configured earlier. [Where problems could occur] The patch moves the reset_arguments() call to the end of main, which means reset_arguments() is no longer called before daemon re-execution (if that branch is taken). If anything in that code path relied on reset_arguments() being called before re-executing, those assumptions could be broken. Any such problems would potentially be seen during daemon re-execution, e.g. when calling systemctl daemon-reexec. [ Original Description ] With systemd v245 as shipped with 20.04, the shutdown sequence does not use the value of `DefaultTimeoutStopSec` to wait for remaining processes, it instead uses the compiled in default of 90s. This is most visible with services that use `KillMode=process` (docker, k8s, k3s, etc...), especially if the remaining processes do not handle `SIGTERM` or choose to ignore it. For example: ``` [ OK ] Finished Reboot. [ OK ] Reached target Reboot. [ 243.652848 ] systemd-shutdown[1]: Waiting for process: containerd-shim, containerd-shim, containerd-shim, fluent-bit --- hangs here for 90s even if DefaultTimeoutStopSec is set to a lower value --- ``` The bug has been fixed upstream here: https://github.com/systemd/systemd/commit/7d9eea2bd3d4f83668c7a78754d201b22 Marc was kind enough to package the patch for 20.04 so I could test it (https://launchpad.net/~mdeslaur/+archive/ubuntu/testing/+sourcepub/13210617/+listing- archive-extra) and with that package, I can confirm that it indeed fixes the issue. Here's a few github issues I stumbled upon while trying to debug this, along with a short writeup of the workaround I ended up using: - https://github.com/moby/moby/issues/41831 - https://github.com/k3s-io/k3s/issues/2400 - https://github.com/systemd/systemd/issues/16991 - https://raby.sh/debugging-90s-hangs-during-shutdown-on-ubuntu-2004.html Of course, it would be much better if all the processes would properly handle `SIGTERM`, but having a way to enforce a maximum wait time at shutdown is a decent workaround. Given that the patch is relatively simple, would it be possible to add it the package for 20.04? Thanks To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1958284/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
