On 4/21/17 00:11, Michael Paquier wrote: > Hmm. I have been actually looking at this solution and I am having > doubts regarding its robustness. In short this would need to be > roughly a two-step process: > - In PostmasterStateMachine(), SIGUSR2 is sent to the checkpoint to > make it call ShutdownXLOG(). Prior doing that, a first signal should > be sent to all the WAL senders with > SignalSomeChildren(BACKEND_TYPE_WALSND). SIGUSR2 or SIGINT could be > used. > - At reception of this signal, all WAL senders switch to a stopping > state, refusing commands that can generate WAL. > - Checkpointer looks at the state of all WAL senders, looping with a > sleep call of a couple of ms, refusing to launch the shutdown > checkpoint as long as all WAL senders have not switched to the > stopping state. > - In reaper(), once checkpointer is confirmed as stopped, signal again > the WAL senders, and tell them to perform the last loop.
Yeah that looks like a reasonable approach. I'm not sure why in your patch you process got_SIGUSR2 in WalSndErrorCleanup() instead of in the main loop. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers