mq_timedreceive on multiple queues

[Romain Geissler <romain.geissler@gmail.com>]

Hi,

I am currently facing an issue when reading in a set of several posix
queues (let's say 2 different mqueues) from several processes. I
currently use epoll_wait to wait for an incoming message on either
queue on all listening processes, then mq_timedreceive to retrieve it
from the queue.

This is an issue when the number of reader process grows, as if I send
only one message on a queue, all processes are awaken when epoll_wait
returns, and all processes try to fetch the message. I would like to
fix this and wake up only one process when listening to several
queues, removing the useless user/kernel space switchs for the other
listening processes.

Is there any way to run a mq_receive/mq_timedreceive on several
queues, that would wake up only one process? Something more or less
like epoll, but that also fetches a message from the readable queues
before returning.

Thanks,
Romain