From: Alvaro Herrera <alvherre@commandprompt.com>
To: Scott Carey <scott@richrelevance.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Jignesh K. Shah <J.K.Shah@sun.com>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Proposal of tunable fix for scalability of 8.4
Date: Fri, 20 Mar 2009 11:46:01 -0400
Message-ID: <20090320154601.GC8313@alvh.no-ip.org> (raw)
In-Reply-To: <BDFBB77C9E07BE4A984DAAE981D19F961AEE7AFBB5@EXVMBX018-1.exch018.msoutlookonline.net>
References: <603c8f070903191349p5e8fb00as2816581d584fcefd@mail.gmail.com>
<BDFBB77C9E07BE4A984DAAE981D19F961AEE7AFBB5@EXVMBX018-1.exch018.msoutlookonline.net>
Scott Carey escribió:
> Your description (much of which I cut out) is exactly how I understood
> it until Simon Riggs' post which changed my view and understanding.
> Under that situation, waking all shared will leave all XXXXX at the
> front and hence alternate shared/exclusive/shared/exclusive as long as
> both types are contending. Simon's post changed my view. Below is
> some cut/paste from it:
Simon's explanation, however, is at odds with the code.
http://git.postgresql.org/?p=postgresql.git;a=blob;f=src/backend/storage/lmgr/lwlock.c
There is "queue jumping" in the regular (heavyweight) lock manager, but
that's a pretty different body of code.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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Subject: Re: Proposal of tunable fix for scalability of 8.4
In-Reply-To: <20090320154601.GC8313@alvh.no-ip.org>
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