basics: use two channels to control the workflow.

basics/main.go

@@ -0,0 +1,45 @@
+package main
+
+import "fmt"
+
+func walk(ch1, ch2 chan int) {
+	fmt.Println("walk")
+
+	fmt.Println("1")
+	ch1 <- 2
+
+	fmt.Println("2")
+	y := <-ch2
+	fmt.Println("y=", y)
+
+	fmt.Println("3")
+}
+
+func loadWorker(ch1, ch2 chan int) {
+	fmt.Println("loadWorker")
+
+	fmt.Println("4")
+	select {
+	case x := <-ch1:
+		fmt.Println("x=", x)
+		fmt.Println("5")
+
+		select {
+		case ch2 <- x + 5:
+			fmt.Println("6")
+		}
+	}
+	fmt.Println("7")
+
+}
+
+func main() {
+	ch1 := make(chan int)
+	ch2 := make(chan int)
+
+	go loadWorker(ch1, ch2)
+
+	walk(ch1, ch2)
+
+	fmt.Println("Done")
+}