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Date: Fri, 2 Mar 2001 13:15:12 -0800 (PST)
From: Forest Come-Peace <forestc@yahoo.com>
Subject: Re: some reasons why Apache 2.0 threaded is slower than prefork
To: new-httpd@apache.org
In-Reply-To: <OF0AF5538D.DD15116F-ON85256A03.0057C9DD@pok.ibm.com>
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Multi-threaded programming is definately a challenge
and often times programmers didn't realize that their
design has a potentil of running into a risk of
creating dead-lock. Don't be too happy when your
multi-threaded program actually run. 

And yes, there are two known methods of achieving
inter process synchronization--lock and message
passing are the two currently known methods of
achieving inter process synchronization that would
preserve the program logic. Anybody out there known of
any good debugging tool that would let the programmer
do timing analysis and also thread safe analysis on
the program like the capability of analysing the basic
block of a program? Thanks
 
--- John Thompson <johntomp@us.ibm.com> wrote:
> 
> And we won't bore people with the fact we can do
> inter-process message
> queue operations (msgrcv, msgsnd) without a lock
> given certain restrictions
> on the message queue via the S/390 PLO instruction.
> 
> regards,
> 
> John M. Thompson
> Consulting Client IT-Architect
> Financial Services Sector
> IBM Corporation
> Internet: johntomp@us.ibm.com
> Lotus Notes: John Thompson/Poughkeepsie/IBM
> VM: thompson at kgnvmc
> 
> 
> 
> Jeff Trawick <trawickj@bellsouth.net>@bellsouth.net
> on 03/01/2001 08:58:03
> PM
> 
> Please respond to new-httpd@apache.org
> 
> Sent by:  trawick@bellsouth.net
> 
> 
> To:   new-httpd@apache.org
> cc:
> Subject:  Re: some reasons why Apache 2.0 threaded
> is slower than prefork
> 
> 
> 
> Greg Stein <gstein@lyra.org> writes:
> 
> > I once tried to created a lock-less linked-list
> for managing some thread
> > state stuff in Python. I believe that it finally
> came to a point where I
> had
> > a simple proof that you just can't implement a
> read/write linked list in
> a
> > multi-threaded environemnt without a lock. Beats
> me if I can remember the
> > key point, though.
> 
> As long as reasonable restrictions are placed on
> allowable list
> operations (restrictions which are not a problem
> when the list is used
> to maintain a free pool) you can implement a
> lock-free linked list.
> Been there, done that.  On S/390 we commonly use a
> double-word
> compare-and-swap operation.  Other platforms have
> this as well.
> Different instructions are available on still more
> platforms.
> 
> --
> Jeff Trawick | trawickj@bellsouth.net | PGP public
> key at web site:
>       
> http://www.geocities.com/SiliconValley/Park/9289/
>              Born in Roswell... married an alien...
> 
> 
> 


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