https://blog.laofu.online 记录技术和生活 Zola zh Mon, 05 Oct 2020 10:00:00 +0800 Mon, 05 Oct 2020 10:00:00 +0800 bigfish https://blog.laofu.online/blog/regex-cpu/ https://blog.laofu.online/blog/regex-cpu/ <p>这篇文章记录一个正则表达是导致 CPU 高的问题排查。由于无法直接使用线上的代码测试，所以我自己把代码整理了下来，具体代码如下：</p> <pre class="giallo z-l-code z-d-code" ><code data-lang="java"><span class="giallo-l"><span class="z-l-2 z-d-8">public</span><span class="z-l-2 z-d-8"> class</span><span class="z-l-8 z-d-10"> AppMain</span><span> {</span></span> <span class="giallo-l"><span class="z-l-2 z-d-8"> public</span><span class="z-l-2 z-d-8"> static</span><span class="z-l-8 z-d-8"> void</span><span class="z-l-9 z-d-6"> main</span><span>(</span><span class="z-l-8 z-d-8">String</span><span>[</span><span>]</span><span class="z-l-3 z-d-10"> args</span><span>)</span><span class="z-l-2 z-d-8"> throws</span><span class="z-l-8"> InterruptedException</span><span> {</span></span> <span class="giallo-l"><span class="z-l-2 z-d-8"> final</span><span class="z-l-8"> String</span><span class="z-l-3"> regex</span><span class="z-d-8">=</span><span class="z-l-12 z-d-5">&quot;</span><span class="z-l-12 z-d-5">^([a-z0-9A-Z]+[-|</span><span class="z-l-17 z-d-8">\\</span><span class="z-l-12 z-d-5">.]?)+[a-z0-9A-Z]@([a-z0-9A-Z]+(-[a-z0-9A-Z]+)?</span><span class="z-l-17 z-d-8">\\</span><span class="z-l-12 z-d-5">.)+[a-zA-Z]{2,}$</span><span class="z-l-12 z-d-5">&quot;</span><span>;</span></span> <span class="giallo-l"><span class="z-l-2 z-d-8"> final</span><span class="z-l-8"> String</span><span class="z-l-3"> email</span><span class="z-d-8">=</span><span class="z-l-12 z-d-5">&quot;</span><span class="z-l-12 z-d-5">blog.laofu.online.fuweilao@vip.qq.com#</span><span class="z-l-12 z-d-5">&quot;</span><span>;</span></span> <span class="giallo-l"><span class="z-l-13 z-d-8"> for</span><span> (</span><span class="z-l-8 z-d-8">int</span><span class="z-l-3"> i</span><span class="z-d-8"> =</span><span class="z-l-7 z-d-2"> 0</span><span>;</span><span> i </span><span class="z-d-8">&lt;</span><span class="z-l-7 z-d-2"> 1000000</span><span>;</span><span> i</span><span class="z-d-8">++</span><span>)</span><span> {</span></span> <span class="giallo-l"><span class="z-l-8"> Matcher</span><span class="z-l-3"> matcher</span><span class="z-d-8"> =</span><span class="z-l-3"> RegexUtils</span><span>.</span><span class="z-l-9 z-d-6">matcher</span><span>(</span><span>regex</span><span>,</span><span> email</span><span>)</span><span>;</span></span> <span class="giallo-l"><span class="z-l-3"> matcher</span><span>.</span><span class="z-l-9 z-d-6">find</span><span>(</span><span>)</span><span>;</span></span> <span class="giallo-l"><span class="z-l-3"> Thread</span><span>.</span><span class="z-l-9 z-d-6">sleep</span><span>(</span><span class="z-l-7 z-d-2">10</span><span>)</span><span>;</span></span> <span class="giallo-l"><span class="z-l-5 z-d-4">//</span><span class="z-l-5 z-d-4"> matcher.group();</span></span> <span class="giallo-l"><span> }</span></span> <span class="giallo-l"><span> }</span></span> <span class="giallo-l"><span>}</span></span></code></pre> <p>当运行程序的时候，我们可以看到 java 的进程占用了 CPU 了 <code>82.1%</code>,由于我使用的服务器是 1核+2G, 所以 load avg 占用也很高。</p>