最近在写一些奇怪的东西的时候，发现大佬们用go或者其他语言实现的并发任务用了thread.sleep让主进程暂停。

回头一想，妈个鸡我要复制粘贴到node一直循环不合适啊，我也需要暂停来着！

怎么办？？

抓了脑袋一会去npm上找了下相关的包，发现有个叫thread-sleep的包，下载量还挺高。

抱着好奇心去看了下源码，又发现源码相当之骚气

'use strict';var childProcess = require('child_process');var nodeBin = process.argv[0];module.exports = sleep;function sleep(milliseconds) {  var start = Date.now();  if (milliseconds !== Math.floor(milliseconds)) {    throw new TypeError('sleep only accepts an integer number of milliseconds');  } else if (milliseconds < 0) {    throw new RangeError('sleep only accepts a positive number of milliseconds');  } else if (milliseconds !== (milliseconds | 0)) {    throw new RangeError('sleep duration out of range')  }  milliseconds = milliseconds | 0;  var shouldEnd = start + milliseconds;  try {    childProcess.execFileSync(nodeBin, [ '-e',      'setTimeout(function() {}, ' + shouldEnd + ' - Date.now());'    ], {      timeout: milliseconds,    });  } catch (ex) {    if (ex.code !== 'ETIMEDOUT') {      throw ex;    }  }  var end = Date.now();  return end - start;}

黑人问号？？？

这是什么奇怪的实现。

翻阅node文档发现

Synchronous Process Creation#The child_process.spawnSync(), child_process.execSync(), and child_process.execFileSync() methods are synchronous and WILL block the Node.js event loop, pausing execution of any additional code until the spawned process exits.Blocking calls like these are mostly useful for simplifying general-purpose scripting tasks and for simplifying the loading/processing of application configuration at startup.

???

以上三种同步方法会阻塞nodejs的事件循环，除非创建的子进程执行完了，才会继续执行下面的代码。

thread-sleep包的作者正是利用这一特性实现了sleep功能。叹为观止

所以很多时候我们没办法解决现有问题的原因是对文档不熟么？？