On Thu, Apr 23, 2015 at 9:32 AM, Lennart Poettering <lenn...@poettering.net> wrote: >> + <title>Beyond the main process</title> >> + >> + <para>The <varname>KillMode=</varname> option primarily defines >> + behavior up until the point where the main process has gone away. >> + systemd expects that when killed with the signal specified by >> + <varname>KillSignal=</varname>, the main process will kill and >> + reap all the other processes in the control group before >> + exiting itself. > > Well, I don't think this is right. I mean, systemd doesn't really > "expect" this. It's completely OK if daemons leave children around in > this case.
I could avoid the word "expect" but I think it's worth mentioning as those discarded children might not be designed to accept 2 SIGTERMs in "normal" conditions. For example, any child process that uses glib and exits the mainloop from the SIGTERM handler does not really respond well here - it drops the SIGTERM handler after the first one, so the second SIGTERM will cause an immediate/unclean shutdown, which is not "completely OK" from the view of the child. > KillMode= is actually very much about the time after the main process > died. If KillMode=process is specified systemd should not send any > signal to anything but the main process, and that applies to both > SIGTERm and the following SIGKILL: I agree, which is why I specifically only talk about the cgroup/mixed kill modes. >> + <para>If <option>KillMode=control-group</option>, systemd will >> + then send a second <varname>KillSignal=</varname> signal to the >> + remaining processes, which will then be followed by a >> + <constant>SIGKILL</constant> if processes are still around, even >> + if <option>SendSIGKILL=no</option>.</para> > > Hmm, no? SendSIGKILL=no should have the effect of not sending any > SIGKILL at all. Anything else would be a bug. Must be a bug then; I confirmed this is actually what happens by adding logging to the kill syscall implementation in the kernel. >> + <para>Or, if <option>KillMode=mixed</option>, systemd will >> + directly send <constant>SIGKILL</constant> to all remaining members >> + of the control group, regardless of the >> + <varname>SendSIGKILL=</varname> preference.</para> > > Hmm? No, not at all. If you use "mixed", then SIGTERM is is sent to > the main process of the daemon, and SIGKILL to *al* processes of the > daemon if there are any left after the main process exited. That's exactly what I wrote - all of this falls under a paragraph explaining what happens when the main process has already gone. I guess I need to improve the wording. Thanks for your feedback Daniel _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
