io_uring in multithreaded process

Question

I am trying to write a multithreaded server using io_uring. The problem is the function 'io_uring_wait_cqe' requires calling to io_uring_cqe_seen to mark the CQE as seen.

Therefore, in several threads, there may be a situation where the same event is handled in several threads.

Of course, I don't want to use locks, mutex, etc.

What is the best way to work with several threads?

To be clear: you mean thread 1 calls io_uring_wait_cqe and gets CQE 1, and thread 2 calls io_uring_wait_cqe and also gets CQE 1 because thread 1 hasn't marked it as seen? — user253751, Nov 01 '22 at 14:45
> of course, I don't want to use locks, mutex, etc. -- Why not? This seems like the obvious approach to this issue — Carson, Nov 01 '22 at 15:52
Because this is not the most efficient way. I'm looking for something like EPOLLONESHOT in EPOLL — Rachel91, Nov 01 '22 at 16:03

score 0 · Answer 1 · answered Nov 16 '22 at 13:22

the official suggestion from jens axboe is to prefer to use one io_uring per thread. If for some reason you really need thread synchronization an approach could be to have one worker thread that uses io_uring, and other threads use message passing to talk with the working thread.

io_uring in multithreaded process

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