From: Ivan Voras <ivoras@freebsd.org>
To: pgsql-performance@postgresql.org
Subject: Re: Performance under contention
Date: Thu, 25 Nov 2010 13:39:42 +0100
Message-ID: <iclle6$jdq$1@dough.gmane.org> (raw)
In-Reply-To: <4CEA58430200002500037D06@gw.wicourts.gov>
References: <4CEA56600200002500037D03@gw.wicourts.gov>
<4CEA58430200002500037D06@gw.wicourts.gov>
<4CEA58430200002500037D06@gw.wicourts.gov>
On 11/22/10 18:47, Kevin Grittner wrote:
> Ivan Voras<ivoras@freebsd.org> wrote:
>
>> It looks like a hack
>
> Not to everyone. In the referenced section, Hellerstein,
> Stonebraker and Hamilton say:
>
> "any good multi-user system has an admission control policy"
>
> In the case of PostgreSQL I understand the counter-argument,
> although I'm inclined to think that it's prudent for a product to
> limit resource usage to a level at which it can still function well,
> even if there's an external solution which can also work, should
> people use it correctly. It seems likely that a mature admission
> control policy could do a better job of managing some resources than
> an external product could.
I didn't think it would be that useful but yesterday I did some
(unrelated) testing with MySQL and it looks like its configuration
parameter "thread_concurrency" does something to that effect.
Initially I thought it is equivalent to PostgreSQL's max_connections but
no, connections can grow (MySQL spawns a thread per connection by
default) but the actual concurrency is limited in some way by this
parameter.
The comment for the parameter says "# Try number of CPU's*2 for
thread_concurrency" but obviously it would depend a lot on the
real-world load.
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To: pgsql-performance@postgresql.org
Cc: ivoras@freebsd.org
Subject: Re: Performance under contention
In-Reply-To: <iclle6$jdq$1@dough.gmane.org>
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