07-03-2002
System V and POSIX IPCs
I am using SUN 0S 5.7.
My application has a dozen programs running in this machine, each instance of a program having 2 POSIX message queues for itself. Totally around 90 POSIX message queues.
Another small application uses a SYSTEM V shared memory and a message queue.
We face a problem here...whenever we boot up the small application, several instances of the bigger application(which uses POSIX queues) were shutting down. The small application doesnt do anything other than opening a System V shared memory, writes some data in it, and detaches. All IPC keys used in all programs are unique. No signals are handled or passed to other programs. There is absolutely no link between both the applications.
Will the System V and POSIX IPCs clash on any case, when run on the same machine?
Is there different "max queues limit" parameter in the same machine for POSIX and SystemV IPCs?
Deepa
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LEARN ABOUT FREEBSD
mq_close
MQ_CLOSE(2) BSD System Calls Manual MQ_CLOSE(2)
NAME
mq_close -- close a message queue (REALTIME)
LIBRARY
POSIX Real-time Library (librt, -lrt)
SYNOPSIS
#include <mqueue.h>
int
mq_close(mqd_t mqdes);
DESCRIPTION
The mq_close() system call removes the association between the message queue descriptor, mqdes, and its message queue. The results of using
this message queue descriptor after successful return from this mq_close(), and until the return of this message queue descriptor from a sub-
sequent mq_open(), are undefined.
If the process has successfully attached a notification request to the message queue via this mqdes, this attachment will be removed, and the
message queue is available for another process to attach for notification.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
The mq_close() system call will fail if:
[EBADF] The mqdes argument is not a valid message queue descriptor.
SEE ALSO
mq_open(2), mq_unlink(2)
STANDARDS
The mq_close() system call conforms to IEEE Std 1003.1-2004 (``POSIX.1'').
HISTORY
Support for POSIX message queues first appeared in FreeBSD 7.0.
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Elec-
trical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html.
BSD
November 29, 2005 BSD