20130830, size of shared memory region changed

Corinna Vinschen corinna-cygwin@cygwin.com
Sat Aug 31 17:49:00 GMT 2013


On Aug 31 13:28, Christopher Faylor wrote:
> On Sat, Aug 31, 2013 at 06:26:54PM +0200, Corinna Vinschen wrote:
> >On Aug 31 14:00, Denis Excoffier wrote:
> >> Hello,
> >> 
> >> I'm using Cygwin 32 bits. With the 20130830 snapshot i now get many messages like:
> >> "      x [main] y z shared_info::initialize: size of shared memory region changed from 27984 to 21776"
> >> 
> >> where x, y and z vary,
> >> - x is typically a small integer (most often 2 or 3, but occurrences were observed of: 4, 5, 8, 27, even 311)
> >> - y is a program name (tcsh, echo, tr, grep, cut, cat, g++, factor...)
> >> - z is a PID
> >> 
> >> The name "main" and the numbers 27984 and 21776 seem always present.
> >> 
> >> It seems that each process initialization would generate a message. Otherwise, all seems OK.
> >
> >I can't reproduce this.  The size of the shared_info changed with my
> >tape drive related checkin from 2013-08-26, but your error message
> >points to some older process still running, still using the previous
> >DLL.  Since the shared_info region continues to exist, any newer process
> >using the new DLL will find that its idea of the sizeof shared_info
> >doesn't match what has been noted in shared_info itself.  Nothing else
> >can explain this.
> >
> >What bugs me is that the change to the mtinfo structure (only the size
> >of some members were affected) apparently didn't change the value of
> >CURR_SHARED_MAGIC, but I don't think we can change this short-term.
> 
> The magic recalculation is pretty crude.  It only detects changes in shared_info
> itself, not in structures used by shared_info.

The mtinfo structure changed for the first time after its introduction
in 2004.  I guess we can ignore this problem once every 9 years :)


Corinna

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