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538635 (2) [Avatar] Offline
#1
	// Launch a goroutine to monitor when all the work is done.
	go func() {
		// Wait for everything to be processed.
		waitGroup.Wait()

		// Close the channel to signal to the Display
		// function that we can exit the program.
		close(results)
	}()


This is the example code in Listing 2.25, I understand that waitGroup.Wait is waiting all goroutine in group is finished, but why we need to use a new goroutine to call an anonymous function instead of calling waitGroup.Wait() and close(results) just before Display inside Run() method?
538635 (2) [Avatar] Offline
#2
Additional investigation:

It will block the program if I move waitGroup.Wait() and close(results) outside goroutine function. With an unbuffered channel, WaitGroup counter does not count down to zero if it does not Display(read) messages from channel. As the results in channel are not read yet, it blocks at writing result into channel after getting to a size. Once I use a buffered channel with a big number
results := make(chan *Result, 100)
it will no longer block the channel anymore.

So, what is the default unbuffered channel size in this behavior?