On Tue, Jan 06, 2015 at 03:28:09AM +0100, Lennart Poettering wrote: > On Mon, 05.01.15 16:03, Lennart Poettering (lenn...@poettering.net) wrote: > > > On Mon, 05.01.15 15:02, Zbigniew Jędrzejewski-Szmek (zbys...@in.waw.pl) > > wrote: > > > > > What we can do instead is to implement daemon-reexec equivalent for > > > journald. It would simply reexec itself to a new binary and pass all > > > the fds. Some serialization/de-serialization protocol would be necessary > > > to pass information about those stdout connections (whatever is given > > > in the header currently), but this shouldn't be too hard. > > > > A long-standing item on the TODO list is adding a concept for pushing > > fds from services into PID 1, which are then passed back into the > > service on the next start. That way journald could push each new > > stream fd into systemd, and would get the fds passed back via the > > usual socket activation logic. With that in place journald could be > > stopped/restarted any time without any special tool, and even > > reconnect to service stdout/stderr on abnormal termination too a > > certain degree. > > > > machined and logind already implement a reexec scheme similar to this, > > by simply maintaining their state in /run. Of course, things are much > > simpler for them, since they don't have to serialize any fds, but > > extending systemd's service management to have a generic fd store > > would allows us to reuse the same restart concept for journald that we > > already have for logind and machined. > > > > Maybe I should just sit down and implement this... > > I have implemented this now. "systemctl restart systemd-journald" should now > no longer lose the stdout/stderr connections. In fact, even if > journald dies abnormally it should not lose anything now.
Cool! Great to see this fixed. > The API I added to PID 1 for this is pretty simple: via the > sd_notify() stuff send a message with "FDSTORE=1" accompanied by the > fds to store and systemd will do so (subject to FileDescriptorStore= > in the service file, which defaults to 0, i.e. this is actually turned > off by default). The file descriptors are than passed on the next > restart of the service using the usual fd passing. The fds are kept > around by systemd until EPOLLHUP or EPOLLERR is seen on them, or the > service is fully stopped and no jobs queued for it anymore. Zbyszek _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
