Horton

Re: BUG #14830: Missed NOTIFications, PostgreSQL 9.1.24

Tom Lane <tgl@sss.pgh.pa.us>

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Marko Tiikkaja <marko@joh.to>
Cc: Michael Paquier <michael.paquier@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@postgresql.org>
Date: 2017-10-10T13:58:58Z
Lists: pgsql-bugs 
Marko Tiikkaja <marko@joh.to> writes:
> So I managed to accidentally kill and/or restart both servers while trying
> to install debug symbols, but I'm doing a new run now and I noticed
> something interesting: the listening backend's RecentXmin doesn't seem to
> ever go forward.  By my reading of this code, that would mean trouble for
> this piece of code in TransactionIdIsInProgress:

>   if (TransactionIdPrecedes(xid, RecentXmin))
>       return false;

Hmm ... I suppose it's possible that that happens if the listening
backend isn't executing any SQL commands but is just sitting.
While that might describe your test harness, does it describe any
real-world application?

			regards, tom lane

Commits

  1. Fix low-probability loss of NOTIFY messages due to XID wraparound.