IPC,FORK on Windows 2008 Server

Corinna Vinschen corinna-cygwin@cygwin.com
Tue Mar 31 19:15:00 GMT 2009

On Mar 31 14:08, Corinna Vinschen wrote:
> On Mar 31 17:11, Yarlagadda Suresh wrote:
> > Hi,
> > 
> > I am using shmget()/shmat() methods for getting the shared memory.
> > 
> > I had tried running the same program which is given in the previous
> > mention thread, the results are same as mentioned over there.
> I just tried that testcase with Cygwin 1.7 and it appears to work most
> of the time.   Unfortunately I can still reproduce the problem once per
> about 30 forks.
> I'll look into fixing this for Cygwin 1.7.  However, please note that
> there is no *really* foolproof method to fix this due to the way fork
> has to be implemented using Win32 calls.  I can only make it much more
> unlikely than today.

I applied a patch to Cygwin which allocates the shmat() shared memory
regions top-down, same as the mmap() regions.  This should make the
observed effect at fork() pretty unlikely.  The patch will be in the
next Cygwin 1.7.0 test release (in a couple of days).

Thanks for the report,

Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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