Re: 20130830, size of shared memory region changed

[Christopher Faylor <cgf-use-the-mailinglist-please at cygwin dot com>]

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.

cgf

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