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Date: Tue, 6 Aug 2002 09:53:49 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: _exit() missing WSACleanup() call?
Message-ID: <20020806095349.N3921@cygbert.vinschen.de>
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References: <1028578338 DOT 7433 DOT ezmlm AT cygwin DOT com> <200208060544 DOT 29738 DOT pullmoll AT stop1984 DOT com>
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On Tue, Aug 06, 2002 at 05:44:20AM +0200, Juergen Buchmueller wrote:
> It actually seems to be the mmap() implementation which is giving me troubles. 
> [...]
> Now the first mmap() region seems to work fine and how I expected -- just as 
> it works under *nix, too. The 'sibling' child processes can write to each 
> other's memory. However, as soon as any child writes to the second anon + 
> shared mmap() region, the Windows memory usage goes up by an amount which 
> (exactly!?) matches the size of that region -- BTW: this is something like 
> 600KB.
> [...]
> Is there a hidden hierarchy in CYGWIN's mmap() implementation? Or with other 
> words, is writing to an anon + shared mmap()ed region from a sibling process 
> that is not a direct descendant of the parent that created a memory map, but 
> rather a child of another process created by a uber-parent which already 
> exited, something that should work?

In theory, it should.  In theory.

Could you run `strace -f' and look if there's

> I must admit that I am confused by my own code right now and even more by the 
> mmap.cc code and comments. I'm not an experienced multi process + daemon 
> author either. For now I sticked up, because crashing OSes make me sick ;-)

Please, could you try to create a simple testcase which exhibits that
behaviour?  Oh and, could you please tell which OS you're using?

I'm really trying hard to get a mmap() implementation which is as U*X
like as possible.  A simple testcase could help a lot.

> [2] I guess you know the fork2() stuff. It is described at e.g. 
> http://www.erlenstar.demon.co.uk/unix/faq_toc.html#TOC88

No, I didn't know that stuff.  Did you try to change your implementation
so that you use fork() and really wait() for the children?

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

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