From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: Testing LISTEN/NOTIFY more effectively |
Date: | 2019-07-28 00:02:13 |
Message-ID: | 20277.1564272133@sss.pgh.pa.us |
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Andres Freund <andres(at)anarazel(dot)de> writes:
> Polling for notices on the blocked connection before printing anything
> ought to practically be reliable. Theoretically I think it still allows
> for some reordering, e.g. because there was packet loss on one, but not
> the other connection.
As long as it's a local connection, packet loss shouldn't be a problem
;-). I'm slightly more worried about the case of more than one bufferful
of NOTICE messages: calling PQconsumeInput isn't entirely guaranteed to
absorb *all* available input. But for the cases we actually need to
deal with, I think probably the patch as I sent it is OK. We could
complicate matters by going around the loop extra time(s) to verify
that select() thinks no data is waiting, but I doubt it's worth the
complexity.
regards, tom lane
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