On Wed, 28.11.12 22:41, Brandon Black (blbl...@gmail.com) wrote: > The daemon's "fast restart" code does all of the expensive startup > operations in the new daemon first (e.g. parsing large data input), then > signals the existing daemon to shut itself down, waits for it to release > its critical resources (e.g. sockets, pidfile), and finally takes over > those resources and finishes starting itself. Basically it's using the > overlap to avoid long service downtimes during that initial parsing phase > (and if that parsing fails, it leaves the old daemon running to boot).
We specifically don't allow ExecRestart= in order to guarantee that all restarts are comprehensive and really do what is necessary to be done. For example, we consider it a good thing to kill all processes forked off a daemon when we restart the daemon. We can do this easily with the information from the cgroup, and we generally believe that such a killing spree is best done from outside the daemon in question rather from the suicidal daemon itself. That said I do acknowledge that there is a bit of value of supporting daemons which can do reexec on their own, where "reexec" is something between the superficial "reload" and the hardcore "restart". In fact I am kinda interested to implement "reexec" in some of systemd's own services (such as journald), so that open sockets are kept around. Now, the reason why we have no support for a nice "reexec" verb yet is simply because I am a bit afraid of adding something that might turn-out not to be necessary, and that might just be a special case of "reload" after all. I mean, the difference between retsart and reload is kinda complex already, and adding a third verb (plus all the various transitive products of this such as "try-restart", "reload-or-restart" for reexec) makes me feel a bit uncomfortable. Or in other words: I am pretty sure that we should not alter the current restart logic, and should not introduce ExecRestart=. However, we really should think about either introducing ExecReexec= or somehow making ExecReload= useful for reexec-style reloading, too. But I haven't made my mind up on this, how this could look like. Michal, Zbigniew, Kay, do you have ideas about this? Lennart -- Lennart Poettering - Red Hat, Inc. _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
