There might be a way to getaddrinfo asynchronously with io_uring by now. Otherwise just call the synchronous version in another thread and let it time out so the thread exits normally, right? Why bother with pthread_cancel?
No. Getaddrinfo is libc, not the kernel. It is of course possible, but complicated, to implement dns resolution with io_uring, but making it behave the same as glibc is very much a nontrivial piece of work.
The problem is that the standard library function is specified to be blocking (and it's in userspace, so io_uring is not relevant). It's quite possible to do a non-blocking DNS lookup but you have to use a separate non-standard library (like c-ares).
