Fix race condition in IOUringEventLoop that prevents shutdown

bryce-anderson commented 1 year ago

Motivation:

Short lived IOUringEventLoop's can fail to shutdown, being stuck in the read-completion phase. This is because under race conditions we can get a task that skips the submission of the eventFd and then exits.

Modifications:

After setting the initial eventfd read event we flush it. This is a one time cost per-loop and avoids the case where a wakeup was requested but never received because the loop enqueued but didn't submit the interest in receiving those event.

Result:

Less stalled threads on shutdown.

bryce-anderson commented 1 year ago

For details about the debugging done to find this see https://github.com/netty/netty-incubator-transport-io_uring/pull/226

bryce-anderson commented 1 year ago

Discussed with @chrisvest offline, and presuming this is good to go, we should port the test to Netty5.

idelpivnitskiy commented 1 year ago

Thanks a lot for fixing it!

normanmaurer commented 1 year ago

@bryce-anderson can you also open a PR for netty 5 ?

netty / netty-incubator-transport-io_uring

Fix race condition in IOUringEventLoop that prevents shutdown #227