fix waitgroup

example-go-channel/Makefile

@@ -8,6 +8,10 @@ simple:
 	GO111MODULE="off" go build -v -x -o ~/go/bin/simple-worker simple-worker.go
 	simple-worker
 
+main1:
+	GO111MODULE="off" go build -v -x -o ~/go/bin/main1 main.go
+	main1
+
 return-vals:
 	GO111MODULE="off" go build -v -x -o ~/go/bin/return-vals return-vals.go
 	return-vals

example-go-channel/main.go

@@ -12,21 +12,23 @@ func generateNumbers(total int, ch chan<- int, wg *sync.WaitGroup) {
 	defer wg.Done()
 
 	for idx := 1; idx <= total; idx++ {
-		fmt.Printf("START sending %d to channel\n", idx)
+		fmt.Printf("START generateNumbers() sending %d to channel\n", idx)
 		ch <- idx
 		// res, err := (<-r)()
-		fmt.Printf("END sending %d to channel\n", idx)
+		fmt.Printf("END generateNumbers() sending %d to channel\n", idx)
 	}
 	wg.Wait()
-	fmt.Printf("END wg sending to channel\n")
+	fmt.Printf("END generateNumbers() wg sending to channel\n")
 }
 
 func printInt(idx int, ch <-chan int, wg *sync.WaitGroup) {
 	defer wg.Done()
 
+	fmt.Printf("START printInt() for chan range\n")
 	for num := range ch {
 		fmt.Printf("%d: read %d from channel\n", idx, num)
 	}
+	fmt.Printf("START printInt() for chan range\n")
 }
 
 func main() {

example-go-channel/sendFunction.go

@@ -21,7 +21,6 @@ var afunc funcWait
 var wg sync.WaitGroup
 
 func generateNumbers(total int, ch chan<- *funcWait, af *funcWait) {
-	defer wg.Done()
 
 	log.Println("generateNumbers() START total =", total)
 	ch <- af
@@ -33,7 +32,7 @@ func andlabsGoroutine(ch <-chan *funcWait, wg *sync.WaitGroup) {
 
 	log.Println("andlabsGoroutine() START")
 	for f := range ch {
-		log.Println("read f() from channel")
+		log.Println("andlabsGoroutine() read f() from channel")
 		f.f()
 	}
 	log.Printf("andlabsGoroutine() END")
@@ -58,8 +57,10 @@ func main() {
 		afunc.val = idx * 20
 		generateNumbers(idx, functionChan, &afunc)
 	}
+	wg.Done()
 
 	close(functionChan)
+	// close(wg)
 
 	log.Println("Waiting for goroutines to finish...")
 	wg.Wait()