What is go's preferred way to synchronize goroutines

go, goroutine, synchronization

Solution

Use sync.WaitGroup (http://godoc.org/sync#WaitGroup)

func Huge(lst []foo) {
  var wg sync.WaitGroup
  for _, item := range lst {
     wg.Add(1)
     go func() {
         performSlow(item)
         wg.Done()
     }()
  }

  wg.Wait()
  return someValue(lst)
}

Problem

I have an expensive function that I apply on all items of a slice. I'm using goroutines to deal with that, each goroutine dealing with one item of the slice. ``` func Huge(lst []foo) { for _, item := range lst { go performSlow(item) } // How do I synchronize here ? return someValue(lst) } ``` The question is, as shown in the comment, what is the preferred way to wait all goroutines have done their job before calling the `someValue` function ? Passing on a channel to `performSlow` and waiting until everyone has written on it works, but it seems overkill : ``` func Huge(lst []foo) { ch := make(chan bool) for _, item := range lst { go performSlow(item, ch) // performSlow does its job, then writes a dummy value to ch } for i := range lst { _ = <-ch } return someValue(lst) } ``` Is there a better (i.e. more efficient and/or more idiomatic) way to do it ?

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