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Re: [PERFORM] scalability issues on win32

From: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
To: "Dave Page" <dpage(at)vale-housing(dot)co(dot)uk>
Cc: <pgsql-performance(at)postgresql(dot)org>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Magnus Hagander" <mha(at)sollentuna(dot)net>,"Win 32 hackers PGSQL" <pgsql-hackers-win32(at)postgresql(dot)org>
Subject: Re: [PERFORM] scalability issues on win32
Date: 2004-12-02 19:21:53
Message-ID: 6EE64EF3AB31D5448D0007DD34EEB3412A754F@Herge.rcsinc.local (view raw or flat)
Thread:
Lists: pgsql-hackers-win32pgsql-performance
> > This was an intersting Win32/linux comparison. I expected
> > Linux to scale better, but I was surprised how poorly XP
> > scaled.  It reinforces our perception that Win32 is for low
> > traffic servers.
> 
> That's a bit harsh given the lack of any further investigation so far
> isn't it? Win32 can run perfectly well with other DBMSs with hundreds
of
> users.
> 
> Any chance you can profile your test runs Merlin?
> 

Ok, I am starting to strongly suspect the statistics collector of
various kinds of malfeasance.  Right now I am running with the stats
collector off and I am getting much better scalability and much more
deterministic query times...that is, even when under moderate to heavy
load query running times are proportional to the number of users on the
system...the system is purring like a kitten right now with over a 100
users logged in.

This coupled with the fact that I was getting random restarts with the
collector process makes me think that there is some kind of issue with
the ipc between the collector and the backends that is blocking and/or
is being improperly handled after failure.

I was running with statement level stats on under scenarios with
extremely high levels of query activity where the server might be
processing 500-1500 queries/second or more spread out over multiple
backends.

I'll look into this issue more over next several days.  I'll dip back
into the code and see if I can come up with a better
answer...unfortunately I can't run the stats collector on until I can
schedule another load test.

Merlin

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Subject: Re: [PERFORM] scalability issues on win32
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