On Fri, May 19, 2017 at 11:05 AM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Thu, May 18, 2017 at 1:43 PM, Thomas Munro > <thomas.mu...@enterprisedb.com> wrote: >> On Thu, May 11, 2017 at 1:48 PM, Michael Paquier >> <michael.paqu...@gmail.com> wrote: >>> I had my eyes on the WAL sender code this morning, and I have noticed >>> that walsender.c is not completely consistent with the PID lookups it >>> does in walsender.c. In two code paths, the PID value is checked >>> without holding the WAL sender spin lock (WalSndRqstFileReload and >>> pg_stat_get_wal_senders), which looks like a very bad idea contrary to >>> what the new WalSndWaitStopping() does and what InitWalSenderSlot() is >>> doing for ages. >> >> There is also code that accesses shared walsender state without >> spinlocks over in syncrep.c. I think that file could use a few words >> of explanation for why it's OK to access pid, state and flush without >> synchronisation. > > Yes, that is read during the quorum and priority sync evaluation. > Except sync_standby_priority, all the other variables should be > protected using the spin lock of the WAL sender. walsender_private.h > is clear regarding that. So the current coding is inconsistent even > there. Attached is an updated patch.
Also, as Horiguchi-san pointed out earlier, walreceiver seems need the similar fix. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers