Re: Stats collection on Windows - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Stats collection on Windows
Date
Msg-id 23293.1144206131@sss.pgh.pa.us
Whole thread Raw
In response to Stats collection on Windows  ("Peter Brant" <Peter.Brant@wicourts.gov>)
Responses Re: Stats collection on Windows  (mark@mark.mielke.cc)
List pgsql-hackers
"Peter Brant" <Peter.Brant@wicourts.gov> writes:
> I think I've found the cause (or one of the causes) why stats
> collection is unreliable on Windows and I'm wondering about the best way
> to go about fixing it.

> The problem is that process IDs on Windows seem to be assigned without
> much rhyme or reason and it seems to happen relatively frequently that a
> new process will be assigned the same process ID as a process which
> recently died.  If this happens before the backend has been expired out
> of pgstat.c's pgStatBeDead hash, the backend will be missed.

That's an interesting theory, but do you have any actual evidence for it?
The evidence I've seen says that our big problem on Windows is the stats
collector process just quitting due to unexplained piperead() failures.

(I mean, I'd love to blame Microsoft for everything, but even the
Redmond crowd should be able to figure out that recycling process IDs
instantly would be a stupid idea...)
        regards, tom lane


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