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Questions tagged [mqueue]

38 questions
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1 answer

linux mq_open ignores mq_msgsize attribute

All, used to think that I was sane, now not so sure. I am trying to create a message queue whose mq_msgsize attribute is OTHER than 8192, which seems to be the default. I have attached my code below -- it has a number of printf's showing the value.…
Billy Pilgrim
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Number of POSIX queues in the system

I have a strange discrepancy between documentation and reality. The man 7 mq_overview states: /proc/sys/fs/mqueue/queues_max This file can be used to view and change the system-wide limit on the number of message queues…
White Owl
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How to install Python's `ipcqueue` dependency on Windows?

When trying to install Python's ipcqueue on Windows 10, I'm getting the following error: .../ipcqueue/posixmq.h(5): fatal error C1083: Cannot open include file: 'mqueue.h': No such file or directory That's expected, since ipcqueue requires Python…
BubbleMaster
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How to disable JMX port for IBM Websphere MQ?

We have tried disabled the jmx for IBM Websphere client using the following and we continue to see that the port is active when our process is running. JAVA_OPTS="-Dcom.sun.management.jmxremote=false" JAVA_OPTS="${JAVA_OPTS}…
goldel777
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mq_open's oflag argument doesn't reflect actual access bits of created mqueue file

I'm calling mq_open on linux 5.5.6 like so: mq_open("/testing12345", O_RDWR | O_CREAT | O_NONBLOCK, 0777, & (struct mq_attr) {0, 10, 255, 0)); Note that I passed 0777 as the 3rd argument. The function succeeds and the appropriate mqueue is…
bool3max
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How to wait until mqueue creation is available?

I have to write program that heavily uses queues from mqueue.h. The problem is it can easily reach /proc/sys/fs/mqueue/queues_max limit which I cannot change. Is it possible to wait until creation of new queue is available without hard spinning? I…
radrow
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Trouble when reading data into buffer using mqqueue

I'm using mqueue to communicate between threads and I'm having a problem passing objects. The mq_send and mq_receive take a char* as a parameter for the object. I use them the following way. foo* foo = new foo(); foo->set_id(3); mq_send(myQueue,…
Marc
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Configuring ceedling with mqueue.h and -lrt

I'm writing unit tests for a project in C using Throw The Switch's Ceedling/Unity/CMock combo as the unit testing framework. I've run into an interesting dilemma where I'm using mqueue.h in one of my unit tests. When the tests compile, I get gcc…
cjameston
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Posix Message Queues QSIZE Query

When I examine the QSIZE of a message queue using "cat /dev/mqueue/myqueue" before and after doing a mq_send()/mq_receive() there appears to be some residual bytes left on the queue after the mq_recieve(). My little test program is below: #include…
John Duffy
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docker: `fs.mqueue.msg_max` set to 10 in spite of host's being 4096

I'm running docker in rootless mode (I cannot sudo in my own machine). When I run sysctl in the container, fs.mqueue.msg_max is set to 10. I get a permission denied error if I try to change it. However, in the host, it's set to 4096. I've tried…
Ivan Perez
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Should mqueues be protected by semaphores

Should read mq_receive and write mq_send be protected by semaphores when accessing a queue in a multiprocess program or is there any sort of protection alredy built in
federicoporritos84
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Oracle Linux : Bad File Descriptor on mq_send and mq_receive

I have a sample code, using mq_open, mq_send and mq_receive, mq_open works fine but mq_send and mq_received throws me error 9, i.e. bad file descriptor, here is my code, pardon me for badly indented code #include #include…
Saad Siddiqui
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Not able to create multi-threads after increase mqueue message size

In my C software I created 10 threads (multi-thread) and write messages in a message queue. I also created 1 more thread to monitor the queue and drain data out from the other end of the queue. It ran ok, but the message size was stuck as default…
Janice Man
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Can you read messages in camunda like we do in Mqueue ?

can we read messages in camunda like we do in Mqueue ? can camunda be a substitute for Apache camel routing framework ?
Parth Dave
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C mqueue doesn't send or receive the entire message

I tried to implement a simple C program using message queues, however the queue doesn't send or receive messages that are longer than 8 characters. I tried to set up all parameters correctly, but I must be missing something. Below is the code and…
Tom
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