go - How to wait until buffered channel (semaphore) is empty?

Question

I have a slice of integers, which are manipulated concurrently:

ints := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

I'm using a buffered channel as semaphore in order to have a an upper bound of concurrently running go routines:

sem := make(chan struct{}, 2)

for _, i := range ints {
  // acquire semaphore
  sem <- struct{}{}

  // start long running go routine
  go func(id int, sem chan struct{}) {
    // do something

    // release semaphore
    <- sem
  }(i, sem)
}

The code above works pretty well until the last or last two integers are reached, because the program ends before those last go routines are finished.

Question: how do I wait for the buffered channel to drain?

Answer 1

Waitting for answers