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for-loopconcurrencygobehaviorsubroutine

GO - subroutine behaviour in a for loop


I'm having some doubts on my understanding of the behaviour of a go subroutine in a for loop.

From what I understand, when we have a for loop:

for key := range Map {
   go subroutine(Map[key])
}

Where Map has, let's say 3 (key,Value) pairs.

So my understanding is that the subroutine() function will run concurrently using all the Map[Key] values ie subroutine(Map[key1]),subroutine(Map[key2]) and subroutine(Map[key3]) will all run concurrently ?

Is my understanding of concurrent subroutines in a for loop correct?

Thanks!


Solution

  • Yes. Please remember that you will still need the main goroutine alive for these to finish before the program ends. You can use something like sync.WaitGroup:

    wg := new(sync.WaitGroup)
    for key := range Map {
      wg.Add(1)
      go func() {
        subroutine(Map[key])
        wg.Done()
      }
    }
    wg.Wait()
    

    Or if you have something like a server loop going on in the main routine you may not need that at all since your program won't finish until a relevant signal is externally sent to it.

    Hope that helps.