Is putting thread on hold optimal?

Question

Application has an auxiliary thread. This thread is not meant to run all the time, but main process can call it very often.

So, my question is, what is more optimal

Answer 1

If it's a worker thread that has units of work given to it externally, it should definitely be using signalling objects as that will ensure it doesn't use CPU needlessly.

If it has any of its own work to do as well, that's another matter. I wouldn't suspend the thread from another thread (what happens if there's two threads delivering work to it?) - my basic rule is that threads should control their own lifetime with suggestions from other threads. This localizes all control in the thread itself.