Date: Fri, 20 Jul 2007 16:51:39 -0400
From: "Jignesh K. Shah" <J.K.Shah@Sun.COM>
Subject: Re: User concurrency thresholding: where do I look?
In-reply-to: <14909.1184962561@sss.pgh.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Josh Berkus <josh@agliodbs.com>, pgsql-performance@postgresql.org,
	Alvaro Herrera <alvherre@commandprompt.com>
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Organization: Sun Microsystems
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sorry..

The are solaris mutex locks used by the postgresql process.

What its saying is that there are holds/waits in trying to get locks 
which are locked at Solaris user library levels called from the  
postgresql functions:
For example both the following functions are hitting on the same mutex 
lock  0x10059e280  in Solaris Library call:
postgres`AllocSetDelete+0x98
postgres`AllocSetAlloc+0x1c4


I need to enable the DTrace probes on my builds

-Jignesh

Tom Lane wrote:
> "Jignesh K. Shah" <J.K.Shah@Sun.COM> writes:
>   
>> Tom Lane wrote:
>>     
>>> So follow that up --- try to determine which lock is being contended
>>> for.  There's some very crude code in the sources that you can enable
>>> with -DLWLOCK_STATS, but probably DTrace would be a better tool.
>>>       
>
>   
>> Using plockstat -A -s 5 -p $pid
>>     
>
> I don't know what that is, but it doesn't appear to have anything to do
> with Postgres LWLocks or spinlocks, which are the locks I was thinking of.
> Try asking Robert Lor about this --- IIRC he had some dtrace probes to
> work with our locks.
>
> 			regards, tom lane
>