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Re: Stats Collector Oddity

From: Chris Browne <cbbrowne(at)acm(dot)org>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Stats Collector Oddity
Date: 2006-12-21 15:32:51
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Lists: pgsql-hackers
tgl(at)sss(dot)pgh(dot)pa(dot)us (Tom Lane) writes:
> Chris Browne <cbbrowne(at)acm(dot)org> writes:
>> We're getting a bit of an anomaly relating to pg_stat_activity...
>> ...
>> That PID has been dead for several days, but this connection is marked
>> as being open, still, after lo many days.
> This probably just means that the "backend termination" stats message
> got dropped due to heavy load.  That's expected behavior in all pre-8.2
> releases: the stats system was never intended to provide
> guaranteed-exactly-correct status.  PG 8.2 has reimplemented the
> pg_stat_activity view to make it more trustworthy.  (The other stuff is
> still probabilistic, but being just event counters, message loss isn't
> so obvious.)

That seems a *bit* surprising; the system wasn't expected to be under
particularly heavy load during the period in question; I would have
expected "particularly light load."  No matter; there may have been
some brief heavy load to cause this.

There isn't any way, short of restarting the postmaster, to get rid of
that PID, is there?
"High-level languages are a pretty good indicator that all else is
seldom equal." - Tim Bradshaw, comp.lang.lisp

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