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.
"text-align: center">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??
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