X-Spam-Check-By: sourceware.org
To: cygwin AT cygwin DOT com
From: Torfinn Ottesen <Torfinn DOT Ottesen AT gmail DOT com>
Subject:  Re: "fork problem" debugging
Date: Mon, 29 May 2006 15:40:54 +0000 (UTC)
Lines: 79
Message-ID:  <loom.20060529T163847-633@post.gmane.org>
References:  <20060518023929 DOT 65449 DOT qmail AT web31310 DOT mail DOT mud DOT yahoo DOT com> <Pine DOT GSO DOT 4 DOT 63 DOT 0605172342490 DOT 19815 AT access1 DOT cims DOT nyu DOT edu> <loom DOT 20060528T233432-336 AT post DOT gmane DOT org> <20060529095133 DOT GA18356 AT sellafield DOT lysator DOT liu DOT se>
Mime-Version:  1.0
Content-Type:  text/plain; charset=us-ascii
Content-Transfer-Encoding:  7bit
User-Agent: Loom/3.14 (http://gmane.org/)
X-IsSubscribed: yes
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

Peter Ekberg <peda <at> lysator.liu.se> writes:
> 
> On Sun, May 28, 2006 at 10:40:34PM +0000, Torfinn Ottesen wrote:
> > <heavily snipped content>
> <snipping some more>
> 
> >          I did this for three programs, prog1 (commercial, external),
> >          prog2 (inhouse, compiled on Cygwin) and native cygwin prog3:
> >          "echo". I claim that I saw increased increase memory usage 
> >          for prog1 and prog2 - but not for the "echo" program.
> 
> Did you really fork for echo, or did you use a shell builtin by mistake?
> 
> /bin/echo is your friend...
> 
> Cheers,
> Peter
> 
> 

Hm - 
$ which echo # give me: /usr/bin/echo     whereas 
$ type echo  # tells that it is a builtin

... thanks for the question, I am now sure that that it was
the builtin by mistake. I repeated this right now with an 
interesting result:

-------

for i in $(seq 1000)
do
    /usr/bin/echo $i
done

Finding, reading off total commit charge in "Task Manager"
- prior to execting loop three times: 357 400 kb 
- after 3 loops (3000 forks)        : 370 550 kb
After 3000 forks of /usr/bin/echo - about 13.2 MB memory increase.
The value appears to be reasonable constant while writing this.
-------------------
Exiting from my xterm, result : down to about 360 800 kb
Exiting from Cygwin/X wmanager: down to about 342 600 kb
---------------
Starting Cygwin/X with one xterm similar to situation prior to loop:
up to 367 400 kb. About 10 MB more than before looping it three times,
have lost about 10 MB somewhere.
-----
Shutting down Cygwin/X, down to 343 100 kb, starting again,
up to: 367 900 kb. (about the same as above)
------
Does 3000 forks,               up to      : 380 400 kb
Shutting down Cygwin/X and up again, up to: 380 800 kb. 
----
Well, it is repeatable here - memory is lost for each fork. The situation
(lost memory) appears to be unaffected by shutting down and restarting
Cygwin/X (doing this by X-ing).
--------

Because of similarity with previous incidences I believe now that
even this little "/usr/bin/echo" loop can bring down my PC if 
running long enough. 

----
It would be interesting to see if someone else can reproduce
this - I'll ask my collegue to try this one tomorrow.

Regards
Torfinn Ottesen 
(Cygwin on MS Win XP Pro Service Pack 1)

PS:
For what it is worth, I have a slightly modified Cygwin/X:
C:\cygwin\usr\X11R6\bin\startxwin.bat
%RUN% XWin -clipboard -silent-dup-error 
%RUN% xterm -bg FloralWhite -sb -rightbar -e /usr/bin/bash -l
%RUN% wmaker




--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/