On Mo, 14.03.22 23:12, Felip Moll (fe...@schedmd.com) wrote: > > But note that you can also run your main service as a service, and > > then allocate a *single* scope unit for *all* your payloads. > > The main issue is the scope needs a pid attached to it. I thought that the > scope could live without any process inside, but that's not happening. > So every time a user step/job finishes, my main process must take care of > it, and launch the scope again on the next coming job.
Leave a stub process around in it. i.e something similar to "/bin/sleep infinity". > The forked process just does the dbus call, and when the scope is ready it > is moved to the corresponding cgroup (PIDFile=). Hmm? PIDFile= is a property of *services*, not *scopes*. And "scopes" cannot be moved to "cgroups". I cannot parse the above. Did you read up on scopes and services? See https://systemd.io/CGROUP_DELEGATION/, it explains the concept of "scopes". Scopes *have* cgroups, but cannot be moved to "cgroups". > Problem number one: if other processes are in the scope, the dbus call > won't work since I am using the same name all the time, e.g. > slurmstepd.scope. > So I first need to check if the scope exists and if so put the new > slurmstepd process inside. But we still have the race condition, if during > this phase all steps ends, systemd will do the cleanup. Leave a stub process around in it. > Problem number two, there's a significant delay since when creating the > scope, until it is ready and the pid attached into it. The only way it > worked was to put a 'sleep' after the dbus call and make my process wait > for the async call to dbus to be materialized. This is really > un-elegant. If you want to synchronize in the cgroup creation to complete just wait for the JobRemoved bus signal for the job returned by StartTransientUnit(). > If instead I could just ask systemd to delegate a part of the tree for my > processes, then everything would be solved. I don't follow. You can enable delegation on the scope. I mean, that's the reason I suggested to use a scope. > Do you have any other suggestions? Not really, except maybe: please read up on the documentation, it explains a lot of the concepts. Lennart -- Lennart Poettering, Berlin
