From acadb8457fb21738f02c7d12a2b10c678b0103ca Mon Sep 17 00:00:00 2001
From: xiaowei <403828237@qq.com>
Date: Tue, 25 Jan 2022 11:20:56 +0800
Subject: [PATCH] =?UTF-8?q?add:=20waitgroup=E7=9A=84=E5=87=A0=E7=A7=8D?=
 =?UTF-8?q?=E7=94=A8=E6=B3=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 waitgroup/example2/main.go   | 35 +++++++++++++++++++++++++++++++++++
 waitgroup/example2/readme.md |  1 +
 2 files changed, 36 insertions(+)
 create mode 100644 waitgroup/example2/main.go
 create mode 100644 waitgroup/example2/readme.md

diff --git a/waitgroup/example2/main.go b/waitgroup/example2/main.go
new file mode 100644
index 0000000..24c3a6e
--- /dev/null
+++ b/waitgroup/example2/main.go
@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"sync"
+	"time"
+)
+
+/*
+限制并发数量的用法
+*/
+func main() {
+	wg := sync.WaitGroup{}
+	// 最多允许的并发数量
+	limit := make(chan struct{}, 20)
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		limit <- struct{}{}
+		go func(num int) {
+			defer func() {
+				<-limit
+				wg.Done()
+			}()
+			dosth(num)
+		}(i)
+	}
+	wg.Wait()
+}
+
+func dosth(i int) {
+	fmt.Println("do sth-->", strconv.Itoa(i))
+	// 模拟耗时1s
+	time.Sleep(time.Second)
+}
diff --git a/waitgroup/example2/readme.md b/waitgroup/example2/readme.md
new file mode 100644
index 0000000..251bcc2
--- /dev/null
+++ b/waitgroup/example2/readme.md
@@ -0,0 +1 @@
+> 用waitgroup限制并发数量的用法
\ No newline at end of file