Hello Nicolas.
On Wed, Jul 07, 2021 at 02:12:51PM +0200, Nicolas Bock <nicolas.bock@xxxxxxxxxxxxx> wrote:
> Using systemd-248.3-1ubuntu1 on Ubuntu Impish the following
> script produces multiple abandoned sessions:
>
> $ for i in {1..100}; do sleep 0.2; ssh localhost sudo systemctl daemon-reload & ssh localhost sleep 1 & done
> $ sleep 2
> $ jobs -p | xargs --verbose --no-run-if-empty kill -KILL
> $ systemctl | grep abandoned
> session-174.scope loaded active abandoned Session 174 of user ubuntu
> session-175.scope loaded active abandoned Session 175 of user ubuntu
> session-176.scope loaded active abandoned Session 176 of user ubuntu
> session-25.scope loaded active abandoned Session 25 of user ubuntu
>
> I would like to debug this behavior further and understand
> why this is happening but don't know where to look next.
It might be a bit challenging :)
> Is there any information in particular I should look at?
I assume you use hybrid or unified cgroup setup and that the abandoned
scopes are empty (no processes in their cgroups), correct?
My hypothesis is following
// race between scope abandonement, emptiness notification -> abandon comes first
manager_reload
manager_clear_jobs_and_units
unit_release_cgroup
inotify_rm_watch(u->manager->cgroup_inotify_fd, u->cgroup_control_inotify_wd)
[...]
// last process terminates somewhere here but we're not watching emptiness yet
scope_coldplug()
// scope should be checked for emptiness here
I _think_ this could be fixed with the patch
--- a/src/core/scope.c
+++ b/src/core/scope.c
@@ -243,8 +243,8 @@ static int scope_coldplug(Unit *u) {
if (r < 0 && r != -EEXIST)
return r;
}
- } else
- (void) unit_enqueue_rewatch_pids(u);
+ }
+ (void) unit_enqueue_rewatch_pids(u);
}
bus_scope_track_controller(s);
Can you file a Github issue to track this (and possibly try if this
works for you)?
Thanks,
Michal
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