be notified when all background threadpool threads are finished

Question

I have a scenario when I start 3..10 threads with ThreadPool. Each thread does its job and returns to the ThreadPool. What are possible options to be notified in main thread

Answer 1

What about using Semaphore, and set a limit to it as much as your thread pool. Have a method to fetch a Semaphore, to be called when you start your thread, release it when your thread end and raise an event if you've taken up all the Semaphore.