posix ipc message queue Post: 302072081

10 More Discussions You Might Find Interesting

1. Programming

POSIX Message Queue - Settings

How can I increase the POSIX Msg Q parameter SC_MQ_PRIO_MAX? The maximum is defined as 32. Can I increase the number? If so, how? Deepa

2. UNIX for Dummies Questions & Answers

Posix vs System V IPC quesions

What are the differences/similarities between posix and system V ipc and their mechanisms? also, why is system v only limited to inter-process communication on a single node? thanks

3. Linux

POSIX message queue size

Hi all, Please tell me how to change POSIX message queue maximum size? "ulimit" is not a solution because it controls shell resources. But i need to control queue size before login in and starting the shell. It is needed to limit queue size for applications started before login in. Sorry for my...

4. Programming

How to limit max no of message in a posix message queue

Hii can anyone pls tell how to limit the max no of message in a posix message queue. I have made changes in proc/sys/fs/mqueue/msg_max But still whenever i try to read the value of max. message in the queue using attr.mq_curmsgs (where struct mq_attr attr) its giving the default value as 10....

5. Programming

IPC - queue problems

Hi, I�m having a lot of problems when working with message queues, both on HP-UX Systems and Sun Solaris. When we fill a queue with a messages, the system hangs and locks everything that relies on the use of IPC resources. Anyone knows how to eliminate this problem? Thanks, Haroldo Teixeira

6. UNIX for Dummies Questions & Answers

IPC Message Queue. msgrcv doesnt work..

Hi everybody, this is the situation. there is a programm XYZ which opens a message queue with the key 47110815 and waits for a SIGUSR1. After receiving this signal it sends a message with type 100 and a number (as ASCII) in the message-body. I have to write a prog which frist sends the...

7. Programming

kill() function problem in client-server ipc message using 2 FIFOs

I want to have a message send & receive through 2 uni-direction FIFO Flow of data FIFO1 stdin--->parent(client) writefd--->FIFO1-->child(server) readfd FIFO2 child(server) writefd2---->FIFO2--->parent(client) readfd2--->stdout I need to have boundary structed message...

8. Programming

Please help:program hang stuck there signal handling on POSIX Message Queue UNIX C programming

in a single main() function,so need signal handling. Use Posix Message Queue IPC mechanism , can ignore the priority and other linked list message,to implement the scenario: client:Knock Knock server:who's there client: Eric Server:Eric,Welcome. client:exit all process terminated ...

9. Programming

POSIX Message Queue Memory Allocation

Hi, I wanted to know whether the POSIX message queues are statically allocated memory by the kernel based on the parameters specified in the open or as and when we send messages, memory are allocated? Does the kernel reserve the specified memory for the message queue irrespective of whether...

10. Programming

POSIX message queue mq_open directory

hello, I try to test the POSIX mq_open function on book unp like below: #include "unpipc.h" # include <mqueue.h> int main(int argc, char **argv) { int c, flags; mqd_t mqd; flags = O_RDWR | O_CREAT; while ((c = getopt(argc, argv, "e")) != -1) { ...

LEARN ABOUT HPUX

msgmni

msgmni(5)							File Formats Manual							 msgmni(5)

NAME

       msgmni - maximum number of system-wide System V IPC message queues (IDs) allowed

VALUES

   Default
   Failsafe
   Allowed Values
DESCRIPTION

       The tunable specifies the maximum number of system-wide System V IPC message queue identifiers (one per queue).	Each message queue created
       has an identifier (ID) and there is an upper limit of identifiers.

       Applications use the system call to create new queues.  If all IDs have been used, will return

       If a process acquires a message queue, but the process terminates without removing it, the queue and all its  messages  remain.	 Abandoned
       message queues can be removed with the command.	Message queue status can be monitored using the command.

       For more information about System V message queues, refer to the section of the mesg(5) manpage.

   Who Is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       This tunable is dynamic.  Changes to to this tunable take effect immediately.

   When Should the Value of This Tunable Be Raised?
       Raise this tunable when applications require more queues.

   When Should the Value of This Tunable Be Lowered?
       Lower this tunable when the requirement for queues has diminished.

   What are the Side Effects of Lowering the Value?
       Lowering  the value increases the risk of application failure due to the inability to create more message queues.  Lowering the tunable has
       no effect on any active message queues, even if the new tunable value is less than the number of queues created in the system. However,	no
       new queues may be created until the number of active queues falls below the setting of

   What Other Tunable Values Should Be Changed at the Same Time?
       All  the  System  V message queue tunables are interrelated and should be treated as independent variables.  The set must be evaluated as a
       system to ensure the tunables reflect the application requirements.  The message tunables include and Specifically, and tunables  may  need
       adjustment along with changes to the tunable.

WARNINGS

       All  HP-UX kernel tunable parameters are release specific.  This parameter may be removed or have its meaning changed in future releases of
       HP-UX.

       Installation of optional kernel software, from HP or other vendors, may cause changes to tunable  parameter  values.   After  installation,
       some  tunable  parameters may no longer be at the default or recommended values.  For information about the effects of installation on tun-
       able values, consult the documentation for the kernel software being installed.	For information about optional kernel  software  that  was
       factory installed on your system, see at

AUTHOR

       was developed by AT&T.

SEE ALSO

       ipcrm(1), ipcs(1), msgget(2), mesg(5), msgmnb(5), msgtql(5), msgmbs(5).

							     Tunable Kernel Parameters							 msgmni(5)