为什么setTimeout阻止我的Node.js应用程序?

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这个代码,一个Http服务器的典型节点js例子,我已经添加了5秒的延迟来模拟其他地方发生的一些异步工作:

const http = require('http');

const hostname = '127.0.0.1';
const port = 8080;

http.createServer((req, res) => {
  setTimeout(()=>{
      res.writeHead(200, { 'Content-Type': 'text/plain' });
      res.end('Hello World\n');
  },5000);
}).listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

我期望的是,当我打开5个选项卡时,让我们假设在打开每个选项卡之间延迟半秒钟,服务器应该用这个定时或多或少地“响应”每个选项卡:

t=0s - I open first tab
t=0.5s - I open second tab
t=1s - I open third tab
...
t=5s - First tab stops loading, server has replied
t=5.5s - Second tab stops loading, server has replied
t=6s - Third tab stops loading, server has replied
t=6.5s - Fourth tab stops loading, server has replied
t=7s - Fifth tab stops loading, server has replied

但是,我看到的行为如下:

t=0s - I open first tab
t=0.5s - I open second tab
t=1s - I open third tab
...
t=5s - First tab stops loading, server has replied
t=10s - Second tab stops loading, server has replied
t=15s - Third tab stops loading, server has replied
t=20s - Fourth tab stops loading, server has replied
t=25s - Fifth tab stops loading, server has replied

就好像后面的请求在第一个请求完成之前还没有开始运行。我在这里错过了什么吗?我认为Node JS的全部重点是能够从单个线程运行异步启动?

提问于
用户回答回答于

问题不在于你的代码或Node.js - 这是你如何设置你的测试。

~ $ ab -n 10 -c 10 http://127.0.0.1:8080/
This is ApacheBench, Version 2.3 <$Revision: 1663405 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient).....done


Server Software:
Server Hostname:        127.0.0.1
Server Port:            8080

Document Path:          /
Document Length:        12 bytes

Concurrency Level:      10
Time taken for tests:   5.019 seconds
Complete requests:      10
Failed requests:        0
Total transferred:      1130 bytes
HTML transferred:       120 bytes
Requests per second:    1.99 [#/sec] (mean)
Time per request:       5019.151 [ms] (mean)
Time per request:       501.915 [ms] (mean, across all concurrent requests)
Transfer rate:          0.22 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:  5017 5018   0.3   5018    5018
Waiting:     5008 5008   0.2   5008    5009
Total:       5018 5018   0.2   5019    5019
ERROR: The median and mean for the total time are more than twice the standard
       deviation apart. These results are NOT reliable.

Percentage of the requests served within a certain time (ms)
  50%   5019
  66%   5019
  75%   5019
  80%   5019
  90%   5019
  95%   5019
  98%   5019
  99%   5019
 100%   5019 (longest request)
用户回答回答于

似乎这只发生在一些浏览器中,我试着用Safari浏览器,它按预期工作。所以我想Chrome会同时将相同请求的数量限制在相同的资源上

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