On Tue, Mar 8, 2011 at 7:05 AM, Fujii Masao <masao.fu...@gmail.com> wrote: > Yeah, let's think about how shutdown should work. I'd like to propose the > following. Thought? > > * Smart shutdown > Smart shutdown should wait for all the waiting backends to be acked, and > should not cause them to forcibly exit. But this leads shutdown to get stuck > infinitely if there is no walsender at that time. To enable them to be acked > even in that situation, we need to change postmaster so that it accepts the > replication connection even during smart shutdown (until we reach > PM_SHUTDOWN_2 state). Postmaster has already accepted the superuser > connection to cancel backup during smart shutdown. So I don't think that > the idea to accept the replication connection during smart shutdown is so > ugly. > > * Fast shutdown > I agree with you about fast shutdown. Fast shutdown should cause all the > backends including waiting ones to exit immediately. At that time, the > non-acked backend should not return the success, according to the > definition of sync rep. So we need to change a backend so that it gets rid > of itself from the waiting queue and exits before returning the success, > when it receives SIGTERM. This change leads the waiting backends to > do the same even when pg_terminate_backend is called. But since > they've not been acked yet, it seems to be reasonable to prevent them > from returning the COMMIT.
The fast shutdown handling seems fine, but why not just handle smart shutdown the same way? I don't really like the idea of allowing replication connections for longer, and the idea that we don't want to keep waiting for a commit ACK once we're past the point where it's possible for one to occur seems to apply generically to any shutdown sequence. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
