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Re: User concurrency thresholding: where do I look?

From: David Boreham <david_list(at)boreham(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org, Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Subject: Re: User concurrency thresholding: where do I look?
Date: 2007-07-21 03:31:14
Message-ID: 46A17E02.2090807@boreham.org (view raw or flat)
Thread:
Lists: pgsql-performance
Tom Lane wrote:
> Having malloc/free use
> an internal mutex is necessary in multi-threaded programs, but the
> backend isn't multi-threaded.  
>   
Hmm...confused. I'm not following why then there is contention for the 
mutex.
Surely this has to be some other mutex that is in contention, not a heap 
lock ?

It'd be handy to see the call stack for the wait state -- if the thing 
is spending
a significant proportion of its time in contention it should be easy to 
get that with
a simple tool such as pstack or a debugger.



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