I'd go for a different approach: Add some cancellation event for select() to listen to as well. Then, when another thread submits a new event source, it's only

I'd go for a different approach: Add some cancellation event for select() to listen to as well. Then, when another thread submits a new event source, it's only a matter of signalling the cancellation event, so the select() thread can update its poll set. "Non-blocking" sounds very special but for anything except batch programs it should be used by default because whenever there is more than one possible input (inputs can be trivial as a cancellation signal) one can not afford to be blocked. Then again, that doesn't mean that one shouldn't use select(). Unless one goes ultra-high frequency where the CPU is busy almost 100% of the time, select() saves CPU cycles, and decreases response time. Without select(), finding an appropriate polling frequency is a tradeoff between wasted compute cycles and increased response time.