add: waitgroup的用法

waitgroup/example1/main.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"sync"
+	"time"
+)
+
+var wg sync.WaitGroup
+
+// test1 不传递wg，用匿名函数运行
+func test1() {
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		Info("task1")
+	}()
+	go func() {
+		defer wg.Done()
+		Info("task2")
+	}()
+	wg.Wait()
+
+}
+
+//test2 for循环并发
+func test2() {
+	for i := 0; i <= 10; i++ {
+		wg.Add(1)
+		go func(a int) {
+			defer wg.Done()
+			Info("test" + strconv.Itoa(a+1))
+		}(i)
+	}
+	wg.Wait()
+}
+//test3 并发限速
+func test3() {
+	limit := make(chan struct{}, 2)
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		limit <- struct{}{}
+		go func(a int) {
+			defer func() {
+				wg.Done()
+				<-limit
+			}()
+			Info("test" + strconv.Itoa(i+1))
+		}(i)
+
+	}
+	wg.Wait()
+}
+
+func Info(name string) {
+	time.Sleep(time.Second)
+	fmt.Printf("this is a %v task...->%v\n", name, time.Now())
+}