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Not sure about Rust, but in other languages that don't have async: create a queue, spawn a thread with your task, thread with sleep and wait for a message from any of those two. Kill the still running thread when you get the message. Can't say it's incredibly hard (unless it's Javascript or you work in a single-threaded model in general).

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> Kill the still running thread when you get the message

This is extremely difficult. I mentioned elsewhere that the only way to kill a thread is through the pthread_cancel API, which is very dangerous.

Languages with larger runtimes can get around this because they have all sorts of things like global locks or implicit cooperative yielding. So they don't ever have to "kill" a thread, they actually just join it when it yields.

As I understand when you are blocked on I/O and sends a signal to the waiting thread, that system call will simply be released and return an error. Ruby (Java etc.) does make it simple because of GC, so I don't need to worry about file descriptor leaks etc. But talking about Rust, shouldn't it be a part of a thread management? Basically if an error happens during normal blocking system call, it goes through the same sequence, no? E.g. you have to release any thread-local allocations no matter by each way system call was terminated. Rust threads are supposed to be memory safe, not sure about file descriptors. I don't quite understand what you mean by "yielding" though.

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