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Full Discussion: System V and POSIX IPCs
Top Forums Programming System V and POSIX IPCs Post 24016 by Deepa on Wednesday 3rd of July 2002 09:42:09 PM
Old 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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pipcs(1)						      General Commands Manual							  pipcs(1)

NAME
pipcs - report status of POSIX interprocess communication facilities SYNOPSIS
qname]] DESCRIPTION
displays certain information on active POSIX interprocess communication facilities. When no options are specified, displays information in short format for the POSIX message queues and POSIX named semaphores that are currently active in the system. Options The following options restrict the display to the corresponding facilities. (none) This is equivalent to Display details for the POSIX message queue specified in the qname argument. Display the list of processes and users using the POSIX message queues. Display information on active POSIX message queues. Display information on active POSIX named semaphores. Display the creation time and last modification time of the POSIX message queues. The options, and can be used only with the option. The options and are mutually exclusive. The following options add columns of data to the display. See "Column Description" below. (none) Display default columns: for all facilities: Display all columns, as appropriate. This is equivalent to Display largest-allowable-size information: for POSIX message queues: Display information on outstanding usage: for POSIX message queues: for POSIX named semaphores: Column Descriptions The column headings and the meaning of the columns in an listing are given below. The columns are printed from left to right in the order shown below. Facility type: POSIX message queue POSIX named semaphore The facility access modes and flags. The mode consists of nine characters that are interpreted as three sets of three characters each. The first set refers to the owner's permissions, the next to permissions of others in the group of the facility entry, and the last to all others. Within each set, the first character indicates permission to read, the second character indicates permission to write or alter the facility entry, and the last character is currently unused. Read permission is granted. Write permission is granted. Alter permission is granted. The indicated permission is not granted. The login name of the owner of the facility entry. The group name of the group of the owner of the facility entry. The reference count value of the facility entry. Reference count of the POSIX message queue represents number of simultaneous open for the associated one. Similarly reference count of the POSIX named semaphore represents number of process referencing the associated one. The name of the facility entry. The number of messages currently outstanding on the associated POSIX message queue. The maximum number of messages allowed on the associated POSIX message queue. The maximum number of bytes allowed in messages outstanding on the associated POSIX message queue. The current value on the associated POSIX named semaphore. The initial value hold on the associated POSIX named semaphore. WARNINGS
produces only an approximate indication of actual system status because system processes are continually changing while is acquiring the requested information. Do not rely on the exact field widths and spacing of the output, as these will vary depending on the system, the release of HP-UX, and the data to be displayed. EXAMPLES
List the processes and users using the POSIX message queues. Note that "None" is displayed if there are no processes using the POSIX mes- sage queue. pipcs -qP /mq/0 : 1234457645 (root) 5433483354 (vts) /mq/1 : None /mq/2 : 8344835378 (user1) List the processes and users using the POSIX message queue pipcs -qP -N /mq/2 /mq/2 : 8344835378 (user1) List the creation time and last modification time of the POSIX message queues. Ctime denotes creation time and Ltime denotes last modifi- cation time. pipcs -qT /mq/0 : Ctime : Mon Feb 4 05:06:40 PST 2006 Ltime : Mon Feb 6 11:06:40 PST 2006 /mq/abcd : Ctime : Mon Feb 2 03:06:40 PST 2006 Ltime : Mon Feb 5 03:06:40 PST 2006 List the creation time and last modification time of the POSIX message queue pipcs -qT -N /mq/0 /mq/0 : Ctime : Mon Feb 4 05:06:40 PST 2006 Ltime : Mon Feb 6 11:06:40 PST 2006 FILES
Group names User names SEE ALSO
pipcrm(1), mq_close(2), mq_open(2), mq_receive(2), mq_send(2), mq_unlink(2), sem_close(2), sem_open(2), sem_post(2), sem_unlink(2), sem_wait(2). pipcs(1)
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