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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jignesh K. Shah <J.K.Shah@Sun.COM>
Cc: Simon Riggs <simon@2ndquadrant.com>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-performance@postgresql.org, Alvaro Herrera <alvherre@commandprompt.com>
Subject: Re: User concurrency thresholding: where do I look?
Date: Thu, 26 Jul 2007 11:42:48 -0400
Message-ID: <27577.1185464568@sss.pgh.pa.us> (raw)
In-Reply-To: <46A8BD62.2080904@sun.com>
References: <200707190828.59088.josh@agliodbs.com>
	<200707191819.13899.josh@agliodbs.com>
	<15685.1184895926@sss.pgh.pa.us>
	<200707192138.39679.josh@agliodbs.com>
	<46A0FA31.2080208@sun.com>
	<12002.1184955831@sss.pgh.pa.us>
	<46A1055F.9010304@sun.com>
	<12445.1184958793@sss.pgh.pa.us>
	<46A11116.5030905@sun.com>
	<14909.1184962561@sss.pgh.pa.us>
	<46A1205B.8010205@sun.com>
	<15343.1184965054@sss.pgh.pa.us>
	<1185180668.4284.149.camel@ebony.site>
	<23848.1185199901@sss.pgh.pa.us>
	<1185201556.4284.243.camel@ebony.site>
	<25095.1185202498@sss.pgh.pa.us>
	<1185205663.4284.249.camel@ebony.site>
	<1185212261.4284.270.camel@ebony.site>
	<1545.1185214760@sss.pgh.pa.us>
	<46A7D5AD.9000706@sun.com>
	<13162.1185405865@sss.pgh.pa.us>
	<46A8AFDF.3050804@sun.com>
	<26825.1185460816@sss.pgh.pa.us>
	<46A8BD62.2080904@sun.com>

"Jignesh K. Shah" <J.K.Shah@Sun.COM> writes:
> For  600-850 Users: that potential mislabeled CheckPointStartLock  or 
> LockID==12 comes from various sources where the top source (while system 
> is still doing great) comes from:

>               postgres`LWLockAcquire+0x1c8
>               postgres`SimpleLruReadPage_ReadOnly+0xc
>               postgres`TransactionIdGetStatus+0x14

That path would be taking CLogControlLock ... so you're off by at least
one.  Compare the script to src/include/storage/lwlock.h.

			regards, tom lane

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