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异步和多线程自编程 - 1 JavaScript中的异步
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<i class="fa fa-calendar"></i><time datetime="2024-05-31T18:32:00+08:00"> Fri 31 May 2024</time>
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<h2>content</h2>
<ol>
<li>What is asynchronous programming? (JavaScript)
<strong>1.1 怎么在JavaScript中进行异步编程?</strong></li>
<li>其他语言的异步编程</li>
<li>多线程编程 (c++)
a. 什么是多线程？与硬件的关系是什么？
b. 使用多线程意味着什么？
c. 使用多线程的目标是什么？</li>
<li>其他语言的多线程编程</li>
<li>多线程与异步编程的关系 (主要讲GoRotine，分析源码，看一下rust有没有改进)</li>
<li>GPU并行编程</li>
</ol>
<h2>introduction</h2>
<h3>background</h3>
<p>我们这个系列主要是讲异步和多线程。异步和多线程本质上来讲都是为了充分的利用计算资源。</p>
<p>当CPU单核主频的发展速度达到瓶颈之后，往多核CPU发展。同时GPU的并行运算给LLM的发展有着极大的促进作用。当然我这一个系列主要是讲CPU，这里我只是想表明并行计算这个概念在现在这个时代非常重要。</p>
<p>那么异步编程是指什么？它和多线程是什么关系？多线程与硬件的关系是什么？异步编程&多线程编程与并行计算又有什么关系？我们将通过这个系列搞清楚这些问题。</p>
<p>我将会不定期的更新这个系列的文章</p>
<h3>in this article</h3>
<p>在这篇文章里面我会介绍:
1. JavaScript中的异步编程
b. promise
c. await
2. Dive dep into it:怎么判断IO操作有没有结束？(源码)
a. 网络操作
b. 文件操作
c. 有没有浪费资源呢?
对于cpu来讲是没有的，因为就算
3. 头脑风暴
a. 怎么让epoll实现自定义的事件通知</p>
<h2>实验环境</h2>
<p><strong>OS:</strong> Windows 11 21H2 22000.2538</p>
<p><strong>Node.js:</strong> 20.13.1</p>
<h3>Promise</h3>
<p>为什么要讲promise?</p>
<p>代码github链接</p>
<p>画流程图，标注一下与回调函数的关系 callbacks</p>
<p>解释</p>
<h3>await</h3>
<p>“async” 这个单词表达了一个简单的事情：即这个函数总是返回一个 promise，如果正常return，就是resolve(returned value),如果异常或者主动返回一个reject了的promise也可以触发reject</p>
<p>await 接受thenable（什么是thenable，只要这个对象具有符合 Promise/A+ 规范的 then 方法即可），如果不是thenable，是具体的值，会立刻解决</p>
<p>await只能和async配合使用，async可以单独使用。</p>
<h2>怎么判断IO操作有没有结束？(源码)</h2>
<h3>网络操作</h3>
<h3>文件操作</h3>
<h3>异步真的没有浪费资源吗?</h3>
<p>事实上在同步编程里面，如果某线程傻傻等待不做任何事件，CPU也不会浪费资源，因为操作系统会把CPU的时间片分配给其他的进程。但这就是操作系统层面的调度了，但是对于线程层面的调度来讲，还是需要异步操作。那么对于进程层面的调度呢？是可以用多线程来解决的，但是比较麻烦。其实异步操作里面大都用了多线程，异步操作和多线程的关系还是很紧密的。简单来讲，现在的异步操作同时大大简化了多线程的管理。</p>
<p>在讲多线程之前，我们会浏览一下异步操作在其他编程语言上的实现。更有利于我们去了解异步与多线程之间的关系。</p>
<h2>relative resources</h2>
<p><a href="https://x.com/DrJimFan/status/1791514371086250291">GPU programming from Jim Fan</a></p>
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<h4>Related Posts:</h4>
<ul>
<li><a href="https://brycemeng.com/async-and-multithread-programming-1-async-in-javascript-en.html">Async&Multithrad - 1 Async - 1 Async in JavaScript</a></li>
<li><a href="https://brycemeng.com/async-and-multithread-programming-1-async-cn.html">异步和多线程编程 - 1 异步</a></li>
<li><a href="https://brycemeng.com/async-and-multithread-programming-1-async-en.html">Async&Multithrad - 1 Async</a></li>
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