The number of message queues is limited by the number of available file descriptors.
For information about the number of file descriptors, see "File descriptors."
The default maximum number of entries in a queue, and the default maximum size of a queue entry depend on whether you're using the traditional (mqueue) or alternate (mq) implementation of message queues:
| Attribute | Traditional | Alternate |
|---|---|---|
| Number of entries | 1024 | 64 |
| Message size | 4096 | 256 |
For more information, see mqueue and mq in the Utilities Reference, and mq_open() in the QNX Neutrino C Library Reference.