time.After and memory leaks

time.After(time.Duration) is the concurrent alternative for time.Sleep(time.duration).

Mistake

This would result in creating a new time.After instance that is not release until the timer expires for every iteration of this loop/every message received.

func consumer(ch <-chan Event) {
  for {
    select {
    case event := <-ch:
      // ...
    case <-time.After(time.Hour):
      // ...
    }
  }
}

Fix

This is better, but creating a new context every loop is still not great.

func consumer(ch <-chan Event) {
  for {
    ctx, cancel := context.WithTimeout(context.Background(), time.Hour)
    select {
      case event := <-ch:
        cancel()
        // ...
      case <-ctx.Done():
        // ...
    }
  }
}

The more appropriate approach would be to use a timer.

func consumer(ch <-chan Event) {
  timerDuration := 1 * time.Hour
  timer := time.NewTimer(timerDuration)
  for {
    timer.Reset(timerDuration)
    select {
    case event := <-ch:
      // ...
    case <-timer.C:
      // ...
    }
  }
}

References