Re: Race condition in InvalidateObsoleteReplicationSlots()

On 2021-Jun-20, Tom Lane wrote:

> Actually ... isn't there a second race, in the opposite direction?
> IIUC, the point of this is that once we force some WAL to be sent
> to the frozen sender/receiver, they'll be killed for failure to
> respond.  But the advance_wal call is not the only possible cause
> of that; a background autovacuum for example could emit some WAL.
> So I fear it's possible for the 'to release replication slot'
> message to come out before we capture $logstart.  I think you
> need to capture that value before the kill not after.

I accounted for all those things and pushed again.

-- 
Álvaro Herrera       Valdivia, Chile
"I can see support will not be a problem.  10 out of 10."    (Simon Wittber)
      (http://archives.postgresql.org/pgsql-general/2004-12/msg00159.php)