并发 是指在一个时间段内有多个进程在执行。
什么是高并发
定义:高并发(High Concurrency)是使用技术手段使系统可以并行处理很多请求。
关键指标:-响应时间(Response Time)-吞吐量(Throughput)-每秒查询率QPS(Query Per Second) -每秒事务处理量TPS(Transaction Per Second)-同时在线用户数量 如何应对高并发?
高并发意味着单位时间内系统能处理的请求数很高,也就是说系统所能承载的HTTP请求很多,那要应对高并发,就要从HTTP请求处理层面开始,如下是我理解的一个完整的HTTP请求所经历的流程:
1、DNS域名解析将请求域名解析为IP地址。
2、与IP地址对应的服务器网卡建立连接,TCP的三次握手,连接建立并占用
3、服务器操作系统通过连接读取和处理请求
3.1 从连接中读取字节流(IO密集)
3.2 将读取到的字节流转换成HTTP请求(CPU密集)
4、服务器操作系统将HTTP请求转发给WEB Server或者Application Server
4.1 Application在开发逻辑架构中一般会分层,分为表现层、业务层和持久层
5、Application进行业务逻辑处理并准备响应Response
6、Response准备完成,Response通过网卡回写到用户的浏览器(IO密集)
7、TCP连接三次挥手,断开连接
从这个过程中,我们对一个HTTP的请求能有一个感性的认识,基于这个感性的认识,我们能知道这里面几个关键的点:域名解析、连接处理、系统分层,从这几个关键点其实就可以提取出一些应对方法。 请求示例
- [Curl]
- [PHP]
- [PHPsdk]
- [JAVA]
- [C#]
- [Python]
-- 请求示例 url 默认请求参数已经URL编码处理
curl -i "https://api-gw.onebound.cn/taobao/item_get/?key=<您自己的apiKey>&secret=<您自己的apiSecret>&num_iid=652874751412&is_promotion=1"
响应示例
{
"item": {
"num_iid": "520813250866",
"title": "三刃木折叠刀过安检创意迷你钥匙扣钥匙刀军刀随身多功能小刀包邮",
"desc_short": "",
"price": 25.8,
"total_price": 0,
"suggestive_price": 0,
"orginal_price": "25.80",
"nick": "欢乐购客栈",
"num": "832",
"min_num": 0,
"detail_url": "http://item.taobao.com/item.htm?id=520813250866",
"pic_url": "//img.alicdn.com/imgextra/i4/2596264565/TB2p30elFXXXXXQXpXXXXXXXXXX_!!2596264565.jpg",
"brand": "三刃木",
"brandId": "4036703",
"rootCatId": "50013886",
"cid": "50014822",
"favcount": "4824",
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"desc": "<p style="text-align:center;"><span style="color:#ff0000;"><span style="font-size:24.0px;"><strong>小店所有产品都支持刻字,如需刻字,拍之前联系客服即可。</strong></span></span></p> <p style="text-align:center;"><span style="font-size:18.0px;"><strong>炎炎夏日来临,一把随身携带便携式的折叠小刀,<span style="color:#ff0000;">带开瓶器功能</span>,喝酒不用愁。(钥匙刀不带开瓶器功能)</strong></span></p> <p style="text-align:center;"><strong style="color:#000000;line-height:1.5;"><span style="font-size:18.0px;"><span style="line-height:18.0px;">可以当吊牌项链装饰,也可当钥匙扣挂饰, 水果刀 开瓶器 户外防身.</span></span></strong></p> <p style="text-align:center;"><strong style="line-height:1.5;"><span style="font-size:24.0px;">部分客户跟我们反映链子质量还不够好,因此小店已重新订购一批质量更好的链子赠送,<span style="color:#ff0000;">加量不加价</span>,只为让你买的更舒心,戴的更放心。</span></strong></p> <p style="text-align:center;"><span style="font-size:36.0px;"><strong>购买就送<span style="color:#ff0000;">工具刀卡和链子</span>一条</strong></span></p> <p style="text-align:center;"><span style="font-size:36.0px;"><strong><img align="absmiddle" src="//img.alicdn.com/imgextra/i3/2596264565/TB2Sci2jXXXXXXFXpXXXXXXXXXX_!!2596264565.png" size="611x442"> </strong></span></p> <p style="text-align:center;"><span style="font-size:18.0px;"><strong>璀璨钻石套餐包含【SK016D钥匙扣+GJ019C折叠刀+GJ017D工具卡】</strong></span><img align="absmiddle" src="//img.alicdn.com/imgextra/i3/2596264565/TB2wWohmXXXXXX8XXXXXXXXXXXX_!!2596264565.jpg" size="750x600" /></p> <p style="text-align:center;"><span style="font-size:18.0px;"><strong>超凡大师套餐包括【304不锈钢钥匙扣+GJ019C折叠刀+GJ017D工具卡】</strong></span><a href="//item.taobao.com/item.htm?id=520798805877" target="_blank"><img align="absmiddle" src="//img.alicdn.com/imgextra/i4/2596264565/TB2_uiXnFXXXXXBXXXXXXXXXXXX_!!2596264565.jpg_q90.jpg" style="float:none;margin:0.0px;" /></a></p> <p style="text-align:center;"> </p> <p style="text-align:center;"><span style="font-size:18.0px;"><strong>最强王者套餐包括【钛钢钥匙扣+GJ019C折叠刀+GJ017D工具卡】<a href="//item.taobao.com/item.htm?id=520801586805" target="_blank"><img align="absmiddle" src="//img.alicdn.com/imgextra/i4/2596264565/TB2Gm9xnFXXXXbmXXXXXXXXXXXX_!!2596264565.jpg_q90.jpg" style="float:none;margin:0.0px;" /></a> </strong></span></p> <p style="text-align:center;"><img align="absmiddle" src="//img.alicdn.com/imgextra/i3/2596264565/TB28Ox4b77OyuJjSsplXXXqdpXa_!!2596264565.jpg" size="749x553"> <img align="absmiddle" src="//img.alicdn.com/imgextra/i1/2596264565/TB2.mTddVXXXXbeXpXXXXXXXXXX_!!2596264565.jpg" style="line-height:1.5;" size="750x653"><img align="absmiddle" src="//img.alicdn.com/imgextra/i3/2596264565/TB21Ro.jl0lpuFjSszdXXcdxFXa_!!2596264565.jpg" size="750x653"> <img align="absmiddle" src="//img.alicdn.com/imgextra/i4/2596264565/TB2q9CelVXXXXcUXXXXXXXXXXXX_!!2596264565.jpg" size="750x340"><img align="absmiddle" src="//img.alicdn.com/imgextra/i3/2596264565/TB21EX9lVXXXXaXXpXXXXXXXXXX_!!2596264565.jpg" size="750x416"><img align="absmiddle" src="//img.alicdn.com/imgextra/i3/2596264565/TB2udCylVXXXXXgXXXXXXXXXXXX_!!2596264565.jpg_q90.jpg"><img 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标签:1627207,img,2596264565,链子,imgextra,并发,API,详情,com
From: https://blog.51cto.com/u_15973577/6926491