I'm debugging a flaky test right now in Wasmtime's CI, and one interesting behavior I'm seeing is that there's a blocking_receive helper for UDP sockets which tries to wait in a loop, and I was going to add an upper limit to the loop to help time it out. This loop, however, never blocks. The socket is always ready for I/O, despite the receive call not actually returning anything. Still trying to figure out the latter, but for the former I believe one issue is that the subscribe for UDP sockets is either readable or writable readiness right now so if a socket is acting as a server then there's no way to block it for read readiness since it's always writable if you're not writing.