背景 近期在做一个dns服务器切换的演练中出现了如下场景: op重启主dns服务器，期望服务访问经由另外一台从dns服务器进行解析，对线上服务无影响。但实际情况是nodejs服务耗时增加，且出现了部分502。nodejs作为站点渲染层收到请求后会利用axios库向下游服务发起http请求。我们正常情况下计算了进出nodejs的耗时大概在80毫秒以下，但是在重启主dns服务器的时间段内，nodejs耗时超过了1～3分钟。下游服务（java）耗时没有明显增加。 node版本10.16.3，axios使用版本0.19.2，请求下游服务有设置timeout: 3000，但是并未生效。所以本篇借着axios的实现说明一下在node中http模块的timeout有什么需要注意的地方。我们期待的是经过axios传递了timeout参数不论是dns查询还是tcp链接超时都能命中，但目前看并非这样。 准备工作 步骤1: 需要一个resolver.js提供dns解析能力，用来模拟慢dns查询的情况，这段代码主要来自于网络，连域名都没有改。我加了一个sleep函数是为了模拟3秒慢查询。代码如下 // The regular expression keyword in domain name. const domain = /hursing/; // When keyword matched, resolve to this IP. const targetIp = <span...

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Preface Reprinted from betterexplained, I think it’s necessary to retain the original article in case it’s been removed or encounter a 404 response (swoops~). Also, some other references can be found, I recommend utf8 tool for verifying what said in this article and javascript encoding for...

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Unfortunately, though, the workmanlike application of those sound engineering principles isn’t always thrilling — until the software is completed on time and works without surprise. — Jon Bentley Preface Standing on date Aug 1st 2016, we talk about TTI optimization. Keep in mind that we...

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Release Engineering is the part of the software engineering process that is most akin to herding cats. — Chuck Rossi Preface As YUI Blog 34 golden rules had mentioned that, make minimum requests can improve Front-end performance, we often bundle javascript files into less...

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期待毛里求斯已经有段时间了，马克吐温说这里是人间天堂。 从北京出发到香港转机，由香港飞往毛里求斯，来回总共花了9天时间，其中6天5晚在毛求度过，不过我已经决定下次要去至少住10天，原因很简单：太美了。 毛里求斯属于温带海洋性气候，夏季多雨，冬季温暖差不多是每年的5-11月，我们选择4月底5月初出行也正因为此。 第一天－第二天 迎着毛毛细雨我们乘坐的毛里求斯航空抵达了机场，入境后乘车前往提前定好的玛尔贝尔酒店。 毛里求斯航空一水的蓝色主题。 这是一家坐落在东岸，离鹿岛（ile cerf）只有10分钟车程的5星酒店，内部环境很好，接待也很有礼貌，其中有至少3名是中国接待。刚进入酒店休息区就被外面宜人的景色吸引住，此时天空已放晴。 拿到接待的欢迎函，喝了杯饮料后等待房间ready，此时会有中文接待过来讲解酒店的娱乐项目，餐厅以及毛里求斯的文化风情。不一会儿我们就拿到房卡，接待领着进入房间做了简单的电器使用介绍后便离去了，我们收拾一下后迫不及待的来到酒店海岸线，踩在细软的沙滩上，享受正午的阳光。 <img src="/assets/images/20160508/DSC_0974.JPG" alt="" style="width:100%;...

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There are only two kinds of languages: the ones people complain about and the ones nobody uses. — Bjarne Stroustrup Preface This can be a long article, even tedious. It’s caused by a topic of process.nextTick. Javascript developer may face to setTimeout,...

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preface This article was reprinted from post of Facebook engineering team. I have to say that Facebook web team have an excellent opinion in a perfect environment to help them improve their web performance. Their solutions in web architecture inspire me from time to time. I strongly recommend...

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CSS2.1 Specification Snapshot from W3C 8.3.1 Collapsing margins In CSS, the adjoining margins of two or more boxes (which might or might not be siblings) can combine to form a single margin. Margins that combine this way are said to collapse, and the resulting combined margin is called a...

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