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<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title>刘梓</title>
<link href="/atom.xml" rel="self"/>
<link href="http://zclau.com/"/>
<updated>2018-01-25T16:52:30.000Z</updated>
<id>http://zclau.com/</id>
<author>
<name>zclau</name>
<email>[email protected]</email>
</author>
<generator uri="http://hexo.io/">Hexo</generator>
<entry>
<title>线程池执行UncaughtExceptionHandler失效问题分析</title>
<link href="http://zclau.com/2018/01/26/%E7%BA%BF%E7%A8%8B%E6%B1%A0%E6%89%A7%E8%A1%8CUncaughtExceptionHandler%E5%A4%B1%E6%95%88%E9%97%AE%E9%A2%98%E5%88%86%E6%9E%90/"/>
<id>http://zclau.com/2018/01/26/线程池执行UncaughtExceptionHandler失效问题分析/</id>
<published>2018-01-25T16:51:56.000Z</published>
<updated>2018-01-25T16:52:30.000Z</updated>
<content type="html"><![CDATA[<h1 id="场景"><a href="#场景" class="headerlink" title="场景"></a>场景</h1><p>我们知道可以对一个Thread对象设置UncaughtExceptionHandler来进行自定义的未捕捉异常处理。具体可参考上一篇文章<a href="https://www.jianshu.com/p/65fb5d5198e2" target="_blank" rel="external">Thread自定义异常处理</a></p>
<p>但是，如果交由线程池来执行的话，</p>
<figure class="highlight livescript"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div></pre></td><td class="code"><pre><div class="line">public static <span class="literal">void</span> main(String[] args) {</div><div class="line"> Thread task = <span class="keyword">new</span> Thread<span class="function"><span class="params">(() -> {</span></span></div><div class="line"> System.out.println(<span class="string">"Before..."</span>);</div><div class="line"> System.out.println(<span class="number">10</span> / <span class="number">0</span>);</div><div class="line"> System.out.println(<span class="string">"After..."</span>);</div><div class="line"> });</div><div class="line"></div><div class="line"></div><div class="line"> <span class="title">task</span>.<span class="title">setName</span><span class="params">(<span class="string">"Thread-demo"</span>)</span>;</div><div class="line"> <span class="title">task</span>.<span class="title">setUncaughtExceptionHandler</span><span class="params">((t1, e) -> {</span></div><div class="line"> System.out.println(<span class="string">"自定义异常: "</span> + t1);</div><div class="line"> System.out.println(e);</div><div class="line"> });</div><div class="line"></div><div class="line"></div><div class="line"> <span class="title">ExecutorService</span> <span class="title">exec</span> = <span class="title">Executors</span>.<span class="title">newCachedThreadPool</span><span class="params">()</span>;</div><div class="line"> <span class="title">exec</span>.<span class="title">execute</span><span class="params">(task)</span>;</div><div class="line"> <span class="title">exec</span>.<span class="title">shutdown</span><span class="params">()</span>;</div><div class="line"> }</div></pre></td></tr></table></figure>
<p>从代码可以看到，线程task设置了UncaughtExceptionHandler，并交给线程池来执行，结果：<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-057f20be970597f4.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-057f20be970597f4.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>可以看到，结果并不像我们设想的那样，居然没有走我们自己定义的异常处理的方法。</p>
<h1 id="原因"><a href="#原因" class="headerlink" title="原因"></a>原因</h1><p>为什么UncaughtExceptionHandler会失效呢，冷静下来仔细回想一下。从上一篇文章的分析中，我们知道只有为线程设置了UncaughtExceptionHandler，该线程在发生异常时，才会执行对应的uncaughtException方法。</p>
<p>如此说来，提交给线程池执行的时候，有可能实际运行task的线程并不是task线程本身（这可能有点拗口）。如果不是task线程本身，又是谁在执行task呢？于是决定对两种方式进行debug，</p>
<p>1、 线程池执行<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-be6957df6dcbe0f7.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-be6957df6dcbe0f7.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>很明显，当前运行task的是线程池创建的线程”pool-1-thread-1”，而我们只是为线程”Thread-demo”设置了uncaughtExceptionHandler，所以就解释了为什么没有走自定义的处理了。</p>
<p>2、单线程执行<br>把上面的例子改为task.start()执行，再debug<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-2b2663e7710812db.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-2b2663e7710812db.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>可以看到，这一次就是task线程本身也就是”Thread-demo”在执行了，而uncaughtExceptionHandler属性也就不为null。</p>
<h1 id="结论"><a href="#结论" class="headerlink" title="结论"></a>结论</h1><p>1、如果让线程池执行的同时，也能走自定义uncaughtExceptionHandler，可以在task的开头加上<br><figure class="highlight lisp"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line">Thread task = new Thread(() -> {</div><div class="line"> Thread.currentThread(). setUncaughtExceptionHandler((<span class="name">t1</span>, e) -> {</div><div class="line"> System.out.println(<span class="string">"自定义异常: "</span> + t1)<span class="comment">;</span></div><div class="line"> System.out.println(<span class="name">e</span>)<span class="comment">;</span></div><div class="line"> })<span class="comment">;</span></div><div class="line"></div><div class="line"> System.out.println(<span class="string">"Before..."</span>)<span class="comment">;</span></div><div class="line"> System.out.println(<span class="number">10</span> / <span class="number">0</span>)<span class="comment">;</span></div><div class="line"> System.out.println(<span class="string">"After..."</span>)<span class="comment">;</span></div><div class="line"> })<span class="comment">;</span></div></pre></td></tr></table></figure></p>
]]></content>
<summary type="html">
<h1 id="&#x573A;&#x666F;"><a href="#&#x573A;&#x666F;" class="headerlink" title="&#x573A;&#x666F;"></a>&#x573A;&#x666F;</h1><p>&#x6211;&#x4EE
</summary>
<category term="Java" scheme="http://zclau.com/categories/Java/"/>
<category term="多线程" scheme="http://zclau.com/tags/%E5%A4%9A%E7%BA%BF%E7%A8%8B/"/>
</entry>
<entry>
<title>Thread自定义异常处理</title>
<link href="http://zclau.com/2018/01/25/Thread%E8%87%AA%E5%AE%9A%E4%B9%89%E5%BC%82%E5%B8%B8%E5%A4%84%E7%90%86/"/>
<id>http://zclau.com/2018/01/25/Thread自定义异常处理/</id>
<published>2018-01-25T08:01:48.000Z</published>
<updated>2018-01-25T08:03:37.000Z</updated>
<content type="html"><![CDATA[<h1 id="背景"><a href="#背景" class="headerlink" title="背景"></a>背景</h1><p>先来看一个例子<br><figure class="highlight livescript"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div></pre></td><td class="code"><pre><div class="line">Thread t = <span class="keyword">new</span> Thread<span class="function"><span class="params">(() -> {</span></span></div><div class="line"> System.out.println(<span class="string">"Before..."</span>);</div><div class="line"> System.out.println(<span class="number">10</span> / <span class="number">0</span>);</div><div class="line"> System.out.println(<span class="string">"After..."</span>);</div><div class="line"> });</div><div class="line"> <span class="title">t</span>.<span class="title">start</span><span class="params">()</span>;</div></pre></td></tr></table></figure></p>
<p>这段代码运行结果是会抛出一个未捕获的异常<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-5357159889618f98.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-5357159889618f98.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>实际来说，这样是很危险的，因为当线程遇到这种未捕获的异常时，就会立即退出，不会再继续执行之后的代码，这样就无法回收一些系统资源，或者没有关闭当前的连接等等。。。</p>
<h1 id="自定义异常处理"><a href="#自定义异常处理" class="headerlink" title="自定义异常处理"></a>自定义异常处理</h1><p>我们可以为Thread设定<code>UncaughtExceptionHandler</code>,在遇到异常中断时，交由它来处理</p>
<figure class="highlight livescript"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div></pre></td><td class="code"><pre><div class="line"> Thread t = <span class="keyword">new</span> Thread<span class="function"><span class="params">(() -> {</span></span></div><div class="line"> System.out.println(<span class="string">"Before..."</span>);</div><div class="line"> System.out.println(<span class="number">10</span> / <span class="number">0</span>);</div><div class="line"> System.out.println(<span class="string">"After..."</span>);</div><div class="line"> });</div><div class="line"></div><div class="line"> <span class="title">t</span>.<span class="title">setUncaughtExceptionHandler</span><span class="params">((t1, e) -> {</span></div><div class="line"> System.out.println(<span class="string">"Exception: "</span> + t1);</div><div class="line"> System.out.println(e);</div><div class="line"> });</div><div class="line"></div><div class="line"><span class="title">t</span>.<span class="title">start</span><span class="params">()</span>;</div></pre></td></tr></table></figure>
<h2 id="UncaughtExceptionHandler"><a href="#UncaughtExceptionHandler" class="headerlink" title="UncaughtExceptionHandler"></a>UncaughtExceptionHandler</h2><p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-bd763bec2cf92bc3.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-bd763bec2cf92bc3.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>UncaughtExceptionHandler在Thread类下定义的一个接口，里面只有一个方法uncaughtException，当一个Thread因为异常而终止时，JVM会触发调用dispatchUncaughtException方法，<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-ea01aa16f5c221b2.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-ea01aa16f5c221b2.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>此方法会调用getUncaughtExceptionHandler去找对应的handler<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-db9a27d09e314dad.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-db9a27d09e314dad.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>如果我们没有自定义UncaughtExceptionHandler的话，就会由当前线程的ThreadGroup对象来处理。<br>找到handler后，把当前Thread对象以及异常Throwable对象作为参数，传入uncaughtException方法，由该方法来处理这次异常。</p>
<p>文章开头例子的运行结果，就是由ThreadGroup的uncaughtException来输出那一堆的异常栈信息。</p>
]]></content>
<summary type="html">
<h1 id="&#x80CC;&#x666F;"><a href="#&#x80CC;&#x666F;" class="headerlink" title="&#x80CC;&#x666F;"></a>&#x80CC;&#x666F;</h1><p>&#x5148;&#x676
</summary>
<category term="Java" scheme="http://zclau.com/categories/Java/"/>
<category term="多线程" scheme="http://zclau.com/tags/%E5%A4%9A%E7%BA%BF%E7%A8%8B/"/>
</entry>
<entry>
<title>常用JVM Crash分析</title>
<link href="http://zclau.com/2017/12/29/%E5%B8%B8%E7%94%A8JVM-Crash%E5%88%86%E6%9E%90/"/>
<id>http://zclau.com/2017/12/29/常用JVM-Crash分析/</id>
<published>2017-12-29T15:25:21.000Z</published>
<updated>2017-12-29T15:25:48.000Z</updated>
<content type="html"><![CDATA[<h1 id="1-JVM-的Error文件"><a href="#1-JVM-的Error文件" class="headerlink" title="1. JVM 的Error文件"></a>1. JVM 的Error文件</h1><p>JDK在意外退出时，会该程序的运行目录生成一个hs<em>error</em>{PID}.log的Error文件，提供一些基本的信息。</p>
<figure class="highlight mel"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">-XX:ErrorFile=${LOGDIR}/hs_err_%p.<span class="keyword">log</span></div></pre></td></tr></table></figure>
<h1 id="2-CoreDump"><a href="#2-CoreDump" class="headerlink" title="2. CoreDump"></a>2. CoreDump</h1><p>在启动脚本中加入<br><figure class="highlight bash"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line"><span class="built_in">ulimit</span> -c unlimited</div></pre></td></tr></table></figure></p>
<p>在进程意外退出时, 将生成CoreDump文件, 在该应用的执行目录下，有一个core.{PID} 文件。</p>
<p>如果没找到，进行全局搜索。</p>
<figure class="highlight golo"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">find</span> / -name core.* <span class="number">2</span>>/dev/<span class="literal">null</span></div></pre></td></tr></table></figure>
<p>如果想固定目录，需要修改内核参数，修改/etc/sysctl.conf，增加</p>
<figure class="highlight awk"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">kernel.core_pattern=<span class="regexp">/apps/</span>logs<span class="regexp">/core</span></div></pre></td></tr></table></figure>
<p>获得coredump文件后，必须在服务器上，使用运行该应用的java, 可获得下列内容</p>
<ul class="ui list">
<li>获得threaddump</li>
</ul>
<figure class="highlight dts"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">jstack <span class="meta-keyword">/apps/</span>svr<span class="meta-keyword">/jdk/</span>bin/<span class="class">java </span>{coredump_file} > <span class="meta-keyword">/tmp/</span>threaddump.log</div></pre></td></tr></table></figure>
<ul class="ui list">
<li>获得heapdump</li>
</ul>
<figure class="highlight gradle"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">jmap -<span class="keyword">dump</span>:format=b,<span class="keyword">file</span>=<span class="regexp">/tmp/</span>heap.hprof <span class="regexp">/apps/</span>svr<span class="regexp">/jdk/</span>bin<span class="regexp">/java {coredump_file}</span></div></pre></td></tr></table></figure>
<ul class="ui list">
<li>gdb大法。</li>
</ul>
<h1 id="2-OOM-Killer"><a href="#2-OOM-Killer" class="headerlink" title="2 OOM Killer"></a>2 OOM Killer</h1><figure class="highlight perl"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">dmesg | <span class="keyword">grep</span> -i <span class="keyword">kill</span></div></pre></td></tr></table></figure>
<p>可以看看有无OOM Killer信息</p>
<p>ps.dmesg中时间戳的转换</p>
<figure class="highlight mel"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">date</span> -d <span class="string">"1970-01-01 UTC `echo "</span>$(<span class="keyword">date</span> +%s)-$(cat /<span class="keyword">proc</span>/uptime|cut -f <span class="number">1</span> -d<span class="string">' '</span>)+{需转换的时间戳}<span class="string">"|bc ` seconds"</span></div></pre></td></tr></table></figure>
]]></content>
<summary type="html">
<h1 id="1-JVM-&#x7684;Error&#x6587;&#x4EF6;"><a href="#1-JVM-&#x7684;Error&#x6587;&#x4EF6;" class="headerlink" title="1. JVM &#x7684;Error&#
</summary>
<category term="Java" scheme="http://zclau.com/categories/Java/"/>
<category term="JVM" scheme="http://zclau.com/tags/JVM/"/>
</entry>
<entry>
<title>常用Heap分析</title>
<link href="http://zclau.com/2017/12/29/%E5%B8%B8%E7%94%A8Heap%E5%88%86%E6%9E%90/"/>
<id>http://zclau.com/2017/12/29/常用Heap分析/</id>
<published>2017-12-29T15:23:31.000Z</published>
<updated>2017-12-29T15:24:51.000Z</updated>
<content type="html"><![CDATA[<h1 id="1-Heap统计信息"><a href="#1-Heap统计信息" class="headerlink" title="1. Heap统计信息"></a>1. Heap统计信息</h1><ul class="ui list">
<li>打印heap信息，如新老代大小，使用率。</li>
</ul>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">jmap -heap <span class="tag"><<span class="name">PID</span>></span></div></pre></td></tr></table></figure>
<h1 id="2-对象统计信息"><a href="#2-对象统计信息" class="headerlink" title="2. 对象统计信息"></a>2. 对象统计信息</h1><ul class="ui list">
<li>打印所有heap对象的统计信息，如对象的个数与所占大小。</li>
</ul>
<figure class="highlight groovy"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div></pre></td><td class="code"><pre><div class="line"><span class="comment">// 打印所有对象的信息</span></div><div class="line">jmap -histo PID > <span class="regexp">/tmp/</span>histo.log</div><div class="line"></div><div class="line"><span class="comment">// 仅打印存活对象的信息</span></div><div class="line">jmap -<span class="string">histo:</span>live PID > <span class="regexp">/tmp/</span>histo-live.log</div></pre></td></tr></table></figure>
<blockquote>
<p>不要随便加 -F 参数，可能把进程搞崩溃，仅当JVM已经假死状态，才用-F最后一搏。live参数实际效果是先执行一次Full GC清理掉已经过期的对象，因此要注意对线上业务的超时影响，尽量摘流量执行。</p>
</blockquote>
<ul class="ui list">
<li>打印各个分代中的对象统计信息，见<a href="https://github.com/alibaba/TBJMap" target="_blank" rel="external">TBJMap</a> </li>
</ul>
<h1 id="3-获取HeapDump"><a href="#3-获取HeapDump" class="headerlink" title="3. 获取HeapDump"></a>3. 获取HeapDump</h1><figure class="highlight stylus"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div></pre></td><td class="code"><pre><div class="line"><span class="comment">// 获取所有对象的dump</span></div><div class="line">jmap -dump:format=<span class="selector-tag">b</span>,file=/tmp/heap<span class="selector-class">.hprof</span> <PID></div><div class="line"></div><div class="line"><span class="comment">// 获取存活对象的dump，实际效果是先执行一次FULL GC</span></div><div class="line">jmap -dump:live,format=<span class="selector-tag">b</span>,file=/tmp/heap-live<span class="selector-class">.hprof</span> <PID></div></pre></td></tr></table></figure>
<blockquote>
<p>heap dump会造成JVM比较长时间的停顿，必须摘流量执行</p>
</blockquote>
<p>dump文件一定要zip后再传输，节约不少时间</p>
<figure class="highlight stylus"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">tar -zcf /tmp/heap<span class="selector-class">.hprof</span><span class="selector-class">.gz</span> /tmp/heap.hprof</div></pre></td></tr></table></figure>
<h1 id="4-分析HeapDump"><a href="#4-分析HeapDump" class="headerlink" title="4. 分析HeapDump"></a>4. 分析HeapDump</h1><p>使用JDK自带的VisaulVM(以jvisualvm启动)或Eclipse的MAT均可</p>
<p>留意对象有两个大小，很多时候<code>Retained Size</code>更有意义：</p>
<ul class="ui list">
<li>本身大小(Shallow Size)：对象本来的大小。</li>
<li>保留大小(Retained Size)： 当前对象大小 + 当前对象直接或间接引用到的对象的大小总和。</li>
</ul>
<p>注意，Eclipse MAT分析时，如果想看到非存活状态的对象，需要特别勾选。</p>
<h1 id="5-分析HeapDump进阶"><a href="#5-分析HeapDump进阶" class="headerlink" title="5. 分析HeapDump进阶"></a>5. 分析HeapDump进阶</h1><p>使用OQL进行高级查询。</p>
<ul class="ui list">
<li><a href="https://visualvm.github.io/documentation.html" target="_blank" rel="external">VisualVM的OQL语法</a></li>
</ul>
<h1 id="6-Out-Of-Memory时自动HeapDump"><a href="#6-Out-Of-Memory时自动HeapDump" class="headerlink" title="6. Out Of Memory时自动HeapDump"></a>6. Out Of Memory时自动HeapDump</h1><p>OOM时生成HeapDump文件.<br><figure class="highlight groovy"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">-<span class="string">XX:</span>+HeapDumpOnOutOfMemoryError -<span class="string">XX:</span>HeapDumpPath=${LOGDIR}/</div></pre></td></tr></table></figure></p>
]]></content>
<summary type="html">
<h1 id="1-Heap&#x7EDF;&#x8BA1;&#x4FE1;&#x606F;"><a href="#1-Heap&#x7EDF;&#x8BA1;&#x4FE1;&#x606F;" class="headerlink" title="1. Heap&#x7EDF;&
</summary>
<category term="Java" scheme="http://zclau.com/categories/Java/"/>
<category term="JVM" scheme="http://zclau.com/tags/JVM/"/>
</entry>
<entry>
<title>Gson ParameterizedTypeImpl初始化校验参数失败问题</title>
<link href="http://zclau.com/2017/12/22/Gson-ParameterizedTypeImpl%E5%88%9D%E5%A7%8B%E5%8C%96%E6%A0%A1%E9%AA%8C%E5%8F%82%E6%95%B0%E5%A4%B1%E8%B4%A5%E9%97%AE%E9%A2%98/"/>
<id>http://zclau.com/2017/12/22/Gson-ParameterizedTypeImpl初始化校验参数失败问题/</id>
<published>2017-12-22T14:32:26.000Z</published>
<updated>2017-12-26T02:12:46.000Z</updated>
<content type="html"><![CDATA[<h1 id="问题背景"><a href="#问题背景" class="headerlink" title="问题背景"></a>问题背景</h1><p>今天在对某个接口做junit测试时，报如下错误</p>
<p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-c33bef422e7f3680.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-c33bef422e7f3680.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>发生错误的本质就是：某个bean在初始化时使用了gson做参数类型映射， 旗下ParameterizedTypeImpl 解析泛型数据时出错，导致创建bean失败，从而导致spring 容器启动失败</p>
<p>而奇怪的是，通过gradle打包运行却是正常的，但跑junit测试却一直报错。</p>
<h1 id="分析"><a href="#分析" class="headerlink" title="分析"></a>分析</h1><p>从堆栈错误可以看到，是在初始化ParameterizedTypeImpl时，调用checkArgument方法时报错， 这时用的gson版本是2.2.2。找到对应的源码位置<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-5b841939f074f386.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-5b841939f074f386.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>然后再来看看客户端初始化ParameterizedTypeImpl传入的参数：<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-72b8836e2f0b8418.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-72b8836e2f0b8418.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<ul class="ui list">
<li>ownerType是null</li>
<li>rawType是ClientService类下的一个静态内部类Response</li>
</ul>
<p>第一个checkArgument校验，ownerType不为null或者rawType不是内部类的条件明显不满足，所以就是在这里抛的illegalArgumentException。</p>
<p>通过gradle打包方式运行，发现使用的是gson 2.8.0（这里注意一下，我们的系统同时存在2.2.2， 2.6.2以及2.8.0版本的gson，gralde解决版本冲突的策略是选取最新的那个版本），没有抛错，而2.8.0对应ParameterizedTypeImpl初始化的代码<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-ec31e8288b975523.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-ec31e8288b975523.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>可以看到2.8.0对应的校验条件发生了变化：</p>
<ul class="ui list">
<li>ownerType不为null 或</li>
<li>rawType是静态类，或者不是内部类</li>
</ul>
<p>我们的Response类是静态类，所以通过校验，没有报错。</p>
<h1 id="解决办法"><a href="#解决办法" class="headerlink" title="解决办法"></a>解决办法</h1><ul class="ui list">
<li>强制使用gson 2.8.0，具体参考 <a href="https://docs.gradle.org/current/dsl/org.gradle.api.artifacts.ResolutionStrategy.html" target="_blank" rel="external">Gradle ResolutionStrategy</a></li>
</ul>
<h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><ul class="ui list">
<li>ParameterizedTypeImpl初始化从2.3.0版本开始更改了校验参数的方式的，如果你在使用的时候发现出现参数校验异常，并且使用的是2.2.2及之前的版本，可以考虑升级gson版本</li>
</ul>
]]></content>
<summary type="html">
<h1 id="&#x95EE;&#x9898;&#x80CC;&#x666F;"><a href="#&#x95EE;&#x9898;&#x80CC;&#x666F;" class="headerlink" title="&#x95EE;&#x9898;&#x80CC;&#x6
</summary>
<category term="Java" scheme="http://zclau.com/categories/Java/"/>
<category term="Gson" scheme="http://zclau.com/tags/Gson/"/>
</entry>
<entry>
<title>Jmeter分布式压测</title>
<link href="http://zclau.com/2017/12/08/Jmeter%E5%88%86%E5%B8%83%E5%BC%8F%E5%8E%8B%E6%B5%8B/"/>
<id>http://zclau.com/2017/12/08/Jmeter分布式压测/</id>
<published>2017-12-08T06:43:43.000Z</published>
<updated>2017-12-08T06:44:49.000Z</updated>
<content type="html"><![CDATA[<blockquote>
<p>进行性能测试时，由于单台机器模拟并发用户数量有限，希望用多台负载机进行负载模拟。我们可以在多台机器上分别部署Jmeter，然后用其中一台做master，控制其他slave实例产生负载。</p>
</blockquote>
<h1 id="step-one"><a href="#step-one" class="headerlink" title="step one"></a>step one</h1><p>部署节点：假设我部署了三台，分别10.199.206.76、10.199.147.249、10.199.205.113<br>首先确保所有节点：<br>运行相同版本的Jmeter<br>运行相同版本的jdk<br>如果需要用到额外的数据文件，例如我的例子需要用到自定义Java Sampler以及外部properties，每个实例需要各来一份。<br>master还需要保存一份xxx.jmx测试脚本</p>
<p>如何编写自定义Java Sampler可参看 </p>
<p><a href="http://www.jianshu.com/p/f18b69c68459" target="_blank" rel="external">Jmeter使用自定义Java代码压测</a></p>
<h1 id="step-two-（optional）"><a href="#step-two-（optional）" class="headerlink" title="step two （optional）"></a>step two （optional）</h1><p>配置节点：<br>这里我选择10.199.206.76做master，10.199.147.249、10.199.205.113作为slave<br>在master的$JMETER_HOME/bin/jmeter.properties的 remote_hosts属性后配置<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-676cce21bd7aa0ef.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-676cce21bd7aa0ef.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>#step three<br>启动slave<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-66db6dbcecbee800.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-66db6dbcecbee800.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>然后检查一下控制台输出：<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-ffc8094fd02629f8.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-ffc8094fd02629f8.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>检查日志，默认会在当前目录写日志<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-097cb5e688f46bc1.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-097cb5e688f46bc1.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>有以上输出，没有报错，证明slave启动成功</p>
<h1 id="step-four"><a href="#step-four" class="headerlink" title="step four"></a>step four</h1><p>启动master进行压测，有两种启动方式<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-33250028bec43497.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-33250028bec43497.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>或</p>
<p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-6ad1757cdba3b445.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-6ad1757cdba3b445.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>注意：如果step two 没有配置 remote_hosts，就必须用第一条命令，通过-R 指定slave</p>
<p>然后master就会发送指令给slave执行实际的压测，然后会等待接收slave压测的结果<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-68bffc4c5f7cd527.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-68bffc4c5f7cd527.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<h1 id="结果解读"><a href="#结果解读" class="headerlink" title="结果解读"></a>结果解读</h1><p>46303 in 00:00:15 = 3134.7/s 表示 在15秒内发送46303条请求，平均每秒处理3134条<br>Avg：504 表示平均响应时间 504ms<br>Min：3 表示最小响应时间3ms<br>Max：14524 表示最长响应时间14524ms</p>
<h1 id="参考"><a href="#参考" class="headerlink" title="参考"></a>参考</h1><p><a href="http://jmeter.apache.org/usermanual/remote-test.html" target="_blank" rel="external">http://jmeter.apache.org/usermanual/remote-test.html</a></p>
<p><a href="https://jmeter.apache.org/usermanual/jmeter_distributed_testing_step_by_step.pdf" target="_blank" rel="external">https://jmeter.apache.org/usermanual/jmeter_distributed_testing_step_by_step.pdf</a></p>
]]></content>
<summary type="html">
<blockquote>
<p>&#x8FDB;&#x884C;&#x6027;&#x80FD;&#x6D4B;&#x8BD5;&#x65F6;&#xFF0C;&#x7531;&#x4E8E;&#x5355;&#x53F0;&#x673A;&#x5668;&#x6A21;&#x6
</summary>
<category term="性能测试" scheme="http://zclau.com/categories/%E6%80%A7%E8%83%BD%E6%B5%8B%E8%AF%95/"/>
<category term="Jmeter" scheme="http://zclau.com/tags/Jmeter/"/>
</entry>
<entry>
<title>Jmeter使用自定义Java代码压测</title>
<link href="http://zclau.com/2017/11/30/Jmeter%E4%BD%BF%E7%94%A8%E8%87%AA%E5%AE%9A%E4%B9%89Java%E4%BB%A3%E7%A0%81%E5%8E%8B%E6%B5%8B/"/>
<id>http://zclau.com/2017/11/30/Jmeter使用自定义Java代码压测/</id>
<published>2017-11-30T03:27:13.000Z</published>
<updated>2017-11-30T03:27:36.000Z</updated>
<content type="html"><![CDATA[<p>Jmeter有几种Sampler，如果想用自定义Java代码来进行压测，就要使用Java Sampler。</p>
<p>那么如何编写Java Sampler，并引入到jmeter进行压测呢？很简单</p>
<h1 id="step-one"><a href="#step-one" class="headerlink" title="step one"></a>step one</h1><p>首先需要引入依赖<br><figure class="highlight"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div></pre></td><td class="code"><pre><div class="line"><dependency></div><div class="line"> <groupId>org.apache.jmeter</groupId></div><div class="line"> <artifactId>ApacheJMeter_java</artifactId></div><div class="line"> <version>3.3</version></div><div class="line"> <scope>provided</scope></div><div class="line"></dependency></div></pre></td></tr></table></figure></p>
<blockquote>
<p>这里只是编译时需要用到，实际运行时代码会放在 ${JMETER_HOME}/lib/ext 下，${JMETER_HOME}/lib 下已经有对应依赖了，所以 这里 scope设置为provided即可。</p>
</blockquote>
<h1 id="step-two"><a href="#step-two" class="headerlink" title="step two"></a>step two</h1><p>然后就可以编写测试代码了<br><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div><div class="line">41</div><div class="line">42</div><div class="line">43</div><div class="line">44</div><div class="line">45</div><div class="line">46</div><div class="line">47</div><div class="line">48</div><div class="line">49</div><div class="line">50</div><div class="line">51</div><div class="line">52</div><div class="line">53</div><div class="line">54</div><div class="line">55</div><div class="line">56</div><div class="line">57</div><div class="line">58</div><div class="line">59</div><div class="line">60</div><div class="line">61</div><div class="line">62</div><div class="line">63</div><div class="line">64</div><div class="line">65</div><div class="line">66</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">SdkTest</span> <span class="keyword">extends</span> <span class="title">AbstractJavaSamplerClient</span> <span class="keyword">implements</span> <span class="title">Serializable</span> </span>{</div><div class="line"></div><div class="line"> <span class="keyword">private</span> <span class="keyword">static</span> Logger logger = LoggerFactory.getLogger(SdkTest.class);</div><div class="line"></div><div class="line"> <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> ConfigCenter configCenter = ConfigCenterFactory.getConfigCenter();</div><div class="line"></div><div class="line"> <span class="comment">/**</span></div><div class="line"> * 自定义java方法入参的, 设置可用参数及默认值</div><div class="line"> * <span class="doctag">@return</span></div><div class="line"> */</div><div class="line"> <span class="meta">@Override</span></div><div class="line"> <span class="function"><span class="keyword">public</span> Arguments <span class="title">getDefaultParameters</span><span class="params">()</span> </span>{</div><div class="line"> Arguments params = <span class="keyword">new</span> Arguments();</div><div class="line"> params.addArgument(<span class="string">"name"</span>, <span class="string">""</span>);</div><div class="line"> params.addArgument(<span class="string">"tag"</span>, <span class="string">""</span>);</div><div class="line"></div><div class="line"> <span class="keyword">return</span> params;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">/**</span></div><div class="line"> * 每个线程测试前执行一次，做一些初始化工作；</div><div class="line"> * <span class="doctag">@param</span> context</div><div class="line"> */</div><div class="line"> <span class="meta">@Override</span></div><div class="line"> <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setupTest</span><span class="params">(JavaSamplerContext context)</span> </span>{</div><div class="line"> <span class="keyword">super</span>.setupTest(context);</div><div class="line"> }</div><div class="line"></div><div class="line"></div><div class="line"> <span class="comment">/**</span></div><div class="line"> * 开始测试，从args参数可以获得参数值；</div><div class="line"> * <span class="doctag">@param</span> args</div><div class="line"> * <span class="doctag">@return</span></div><div class="line"> */</div><div class="line"> <span class="meta">@Override</span></div><div class="line"> <span class="function"><span class="keyword">public</span> SampleResult <span class="title">runTest</span><span class="params">(JavaSamplerContext args)</span> </span>{</div><div class="line"> String name = args.getParameter(<span class="string">"name"</span>);</div><div class="line"> String tag = args.getParameter(<span class="string">"tag"</span>);</div><div class="line"></div><div class="line"> SampleResult result = <span class="keyword">new</span> SampleResult();</div><div class="line"></div><div class="line"> <span class="keyword">try</span> {</div><div class="line"> result.sampleStart();</div><div class="line"></div><div class="line"> </div><div class="line"> <span class="comment">//这里就是自定义压测的代码</span></div><div class="line"> .........</div><div class="line"> ..........</div><div class="line"> ..........</div><div class="line"> </div><div class="line"> <span class="comment">//请求成功，设置测试结果为成功</span></div><div class="line"> result.setSuccessful(<span class="keyword">true</span>);</div><div class="line"> } <span class="keyword">catch</span> (Exception e) {</div><div class="line"> result.setSuccessful(<span class="keyword">false</span>);</div><div class="line"> e.printStackTrace();</div><div class="line"> } <span class="keyword">finally</span> {</div><div class="line"> result.sampleEnd();</div><div class="line"> }</div><div class="line"> <span class="keyword">return</span> result;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="meta">@Override</span></div><div class="line"> <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">teardownTest</span><span class="params">(JavaSamplerContext context)</span> </span>{</div><div class="line"> <span class="keyword">super</span>.teardownTest(context);</div><div class="line"> }</div><div class="line">}</div></pre></td></tr></table></figure></p>
<blockquote>
<p>需要注意：Sampler类需要扩展JMeter的类org.apache.jmeter.protocol.java.sampler.AbstractJavaSamplerClient 或 实现 org.apache.jmeter.protocol.java.sampler.JavaSamplerClient接口</p>
</blockquote>
<h1 id="step-three"><a href="#step-three" class="headerlink" title="step three"></a>step three</h1><p>编写完成后，通过 mvn package 打成一个jar包，为了方便，我这里打成的是一个fat包，然后讲其放进 $JMETER_HOME/lib/ext目录下</p>
<h1 id="step-four"><a href="#step-four" class="headerlink" title="step four"></a>step four</h1><p>打开Jmeter，创建一个Java Request<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-176d4d6732d414c5.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-176d4d6732d414c5.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>然后就能看到刚才编写的Sampler类了<br><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-6c5514d3ee932347.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-6c5514d3ee932347.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>红色框处可以定义测试的输入，刚才上面的代码例子中的runTest方法中，就可用通过JavaSamplerContext来获取这些输入</p>
<p>然后就可以开心地进行压测了</p>
<h3 id="坑"><a href="#坑" class="headerlink" title="坑"></a>坑</h3><p>1、如果Sampler代码需要获取外部配置的话，例如需要配置zk server、host等配置，而这些配置是在外部properties中的，需要在启动jmeter的时候加上<br><figure class="highlight stylus"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">sh jmeter<span class="selector-class">.sh</span> -Dcom<span class="selector-class">.vipshop</span><span class="selector-class">.mobile</span><span class="selector-class">.serconfig</span>=./configcenter.properties</div></pre></td></tr></table></figure></p>
]]></content>
<summary type="html">
<p>Jmeter&#x6709;&#x51E0;&#x79CD;Sampler&#xFF0C;&#x5982;&#x679C;&#x60F3;&#x7528;&#x81EA;&#x5B9A;&#x4E49;Java&#x4EE3;&#x7801;&#x6765;&#x8FDB;
</summary>
<category term="性能测试" scheme="http://zclau.com/categories/%E6%80%A7%E8%83%BD%E6%B5%8B%E8%AF%95/"/>
<category term="Jmeter" scheme="http://zclau.com/tags/Jmeter/"/>
</entry>
<entry>
<title>性能测试关注的指标</title>
<link href="http://zclau.com/2017/11/29/%E6%80%A7%E8%83%BD%E6%B5%8B%E8%AF%95%E5%85%B3%E6%B3%A8%E7%9A%84%E6%8C%87%E6%A0%87/"/>
<id>http://zclau.com/2017/11/29/性能测试关注的指标/</id>
<published>2017-11-29T14:32:02.000Z</published>
<updated>2017-11-30T03:26:11.000Z</updated>
<content type="html"><![CDATA[<h3 id="性能测试时我们需要关注的指标"><a href="#性能测试时我们需要关注的指标" class="headerlink" title="性能测试时我们需要关注的指标"></a>性能测试时我们需要关注的指标</h3><ul class="ui list">
<li><p>RT：响应时间</p>
</li>
<li><p>TPS：每秒完成事务数</p>
</li>
<li><p>CPU性能指标：利用率、负载</p>
</li>
<li><p>Mem：内存性能指标，可用物理内存、虚拟内存使用率</p>
</li>
<li><p>Disk：磁盘性能指标，Disk Time、IO等待</p>
</li>
<li><p>NetWork：网络指标，带宽使用率、任务队列长度</p>
</li>
</ul>
<ul class="ui list">
<li><p>TCP连接数，可以用netstat命令统计得到</p>
</li>
<li><p>中间件建立的线程池，监控线程状态</p>
</li>
<li><p>JVM性能指标，GC情况、Heap使用情况</p>
</li>
<li><p>CPU负载队列长度</p>
</li>
<li><p>服务器与中间件之间建立的连接数及连接状态</p>
</li>
</ul>
<h3 id="一般性能分析的过程"><a href="#一般性能分析的过程" class="headerlink" title="一般性能分析的过程"></a>一般性能分析的过程</h3><ul class="ui list">
<li>检查RT: 客户端响应时间 </li>
<li>检查TPS: TPS大时RT小， 说明性能良好 </li>
<li>检查负载机资源消耗: 检查CPU使用率 </li>
<li>检查被压服务器的资源消耗: CPU 、 内存、磁盘IO、带宽、响应时间</li>
<li>检查中间件配置: 确定是否有配置参数问题 </li>
<li>数据库服务器: CPU、内存、IO繁忙程度、数据库监控</li>
</ul>
<h3 id="相关参考"><a href="#相关参考" class="headerlink" title="相关参考"></a>相关参考</h3><ul class="ui list">
<li>左耳朵大神写过一篇博客，阐述他对性能测试的一些看法 <a href="https://coolshell.cn/articles/17381.html" target="_blank" rel="external">性能测试应该怎么做?</a></li>
<li>关于GC分析，可以参看<a href="http://www.jianshu.com/p/5ace2a0cafa4" target="_blank" rel="external">初步诊断你的GC</a></li>
</ul>
<p>待续……</p>
]]></content>
<summary type="html">
<h3 id="&#x6027;&#x80FD;&#x6D4B;&#x8BD5;&#x65F6;&#x6211;&#x4EEC;&#x9700;&#x8981;&#x5173;&#x6CE8;&#x7684;&#x6307;&#x6807;"><a href="#&#x6027;
</summary>
<category term="性能测试" scheme="http://zclau.com/categories/%E6%80%A7%E8%83%BD%E6%B5%8B%E8%AF%95/"/>
<category term="性能测试" scheme="http://zclau.com/tags/%E6%80%A7%E8%83%BD%E6%B5%8B%E8%AF%95/"/>
</entry>
<entry>
<title>线程池拒绝策略源码小析</title>
<link href="http://zclau.com/2017/11/10/%E7%BA%BF%E7%A8%8B%E6%B1%A0%E6%8B%92%E7%BB%9D%E7%AD%96%E7%95%A5%E6%BA%90%E7%A0%81%E5%B0%8F%E6%9E%90/"/>
<id>http://zclau.com/2017/11/10/线程池拒绝策略源码小析/</id>
<published>2017-11-10T07:17:15.000Z</published>
<updated>2017-11-10T07:23:19.000Z</updated>
<content type="html"><![CDATA[<ul class="ui list">
<li><p>提交一个新的task到线程池后，此时如果ThreadPool内的所有工作线程都在忙碌时（没有可用的线程去处理该task），并且任务队列也到达界限，这时候就需要用到拒绝策略。</p>
</li>
<li><p>在 java.util.concurrent包下有个RejectedExecutionHandler接口，该接口定义了rejectedExecution方法，用来实现具体的拒绝行为。</p>
</li>
</ul>
<p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-e39226683758c31e.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-e39226683758c31e.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<ul class="ui list">
<li>再往下看，Java预定义了四种拒绝策略：<br><img src="http://upload-images.jianshu.io/upload_images/8923118-08fa4589a940767c.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png"></li>
</ul>
<p>下面就分析一下这四种拒绝策略有什么不一样：</p>
<h3 id="AbortPolicy"><a href="#AbortPolicy" class="headerlink" title="AbortPolicy"></a>AbortPolicy</h3><p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-6d7b6ecd5323eb21.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-6d7b6ecd5323eb21.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>可以看到AbortPolicy其实就是直接抛了个exception，并丢弃该task。</p>
<h3 id="DiscardPolicy"><a href="#DiscardPolicy" class="headerlink" title="DiscardPolicy"></a>DiscardPolicy</h3><p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-0f93f7ce1cedd7e9.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-0f93f7ce1cedd7e9.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>DiscardPolicy什么都没做，静静地丢弃该task</p>
<h3 id="DiscardOldestPolicy"><a href="#DiscardOldestPolicy" class="headerlink" title="DiscardOldestPolicy"></a>DiscardOldestPolicy</h3><p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-80005ac373773c29.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-80005ac373773c29.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>可以看到DiscardOldestPolicy会先通过poll方法，将任务队列的队头，也就是最旧的那个任务remove掉，然后将最新的task放进线程池</p>
<h3 id="CallerRunsPolicy"><a href="#CallerRunsPolicy" class="headerlink" title="CallerRunsPolicy"></a>CallerRunsPolicy</h3><p><a class="magnific-img" href="http://upload-images.jianshu.io/upload_images/8923118-5623a7e77443ac0d.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"><img src="http://upload-images.jianshu.io/upload_images/8923118-5623a7e77443ac0d.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt="image.png" class="ui centered image"></a></p>
<p>可以看到，CallerRunsPolicy就是直接调用Runnable的实例方法run去执行该task，说白了就是该task直接由调用者线程来执行</p>
<h3 id="后记"><a href="#后记" class="headerlink" title="后记"></a>后记</h3><p>当然，以上四种拒绝策略只是jdk预定义的，我们也可以根据实际情况自定义拒绝策略，只需要实现RejectedExecutionHandler接口即可</p>
]]></content>
<summary type="html">
<ul class="ui list">
<li><p>&#x63D0;&#x4EA4;&#x4E00;&#x4E2A;&#x65B0;&#x7684;task&#x5230;&#x7EBF;&#x7A0B;&#x6C60;&#x540E;&#xFF0C;&#x6B64;&#x6
</summary>
<category term="Java" scheme="http://zclau.com/categories/Java/"/>
<category term="Core Java" scheme="http://zclau.com/tags/Core-Java/"/>
</entry>
<entry>
<title>maven依赖调解</title>
<link href="http://zclau.com/2017/07/04/maven%E4%BE%9D%E8%B5%96%E8%B0%83%E8%A7%A3/"/>
<id>http://zclau.com/2017/07/04/maven依赖调解/</id>
<published>2017-07-04T13:35:10.000Z</published>
<updated>2017-07-04T14:01:41.000Z</updated>
<content type="html"><![CDATA[<p>项目有以下依赖：</p>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line"><span class="tag"><<span class="name">dependency</span>></span></div><div class="line"> <span class="tag"><<span class="name">groupId</span>></span>com.vips.components<span class="tag"></<span class="name">groupId</span>></span></div><div class="line"> <span class="tag"><<span class="name">artifactId</span>></span>vips-common-cache<span class="tag"></<span class="name">artifactId</span>></span></div><div class="line"> <span class="tag"><<span class="name">version</span>></span>2.0<span class="tag"></<span class="name">version</span>></span></div><div class="line"><span class="tag"></<span class="name">dependency</span>></span></div><div class="line"><span class="tag"><<span class="name">dependency</span>></span></div><div class="line"> <span class="tag"><<span class="name">groupId</span>></span>org.apache.poi<span class="tag"></<span class="name">groupId</span>></span></div><div class="line"> <span class="tag"><<span class="name">artifactId</span>></span>poi<span class="tag"></<span class="name">artifactId</span>></span></div><div class="line"> <span class="tag"><<span class="name">version</span>></span>3.9<span class="tag"></<span class="name">version</span>></span></div><div class="line"><span class="tag"></<span class="name">dependency</span>></span></div></pre></td></tr></table></figure>
<p>其中</p>
<p>vips-common-cache —> vip-common-util —> commons-codec(1.6)</p>
<p>poi —> commons-codec(1.5)</p>
<p>使用 mvn dependency:tree 分析依赖后，发现maven实际使用的是 poi下的commons-codec(1.5)</p>
<p><a class="magnific-img" href="http://7xp2k4.com1.z0.glb.clouddn.com/5FB88141-2E41-47A3-B09C-AD6986A6A56E.png"><img src="http://7xp2k4.com1.z0.glb.clouddn.com/5FB88141-2E41-47A3-B09C-AD6986A6A56E.png" alt="" class="ui centered image"></a></p>
<p>再来看以下情形：</p>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line"><span class="tag"><<span class="name">dependency</span>></span></div><div class="line"> <span class="tag"><<span class="name">groupId</span>></span>org.apache.httpcomponents<span class="tag"></<span class="name">groupId</span>></span></div><div class="line"> <span class="tag"><<span class="name">artifactId</span>></span>httpclient<span class="tag"></<span class="name">artifactId</span>></span></div><div class="line"> <span class="tag"><<span class="name">version</span>></span>4.4.1<span class="tag"></<span class="name">version</span>></span></div><div class="line"><span class="tag"></<span class="name">dependency</span>></span></div><div class="line"><span class="tag"><<span class="name">dependency</span>></span></div><div class="line"> <span class="tag"><<span class="name">groupId</span>></span>org.apache.poi<span class="tag"></<span class="name">groupId</span>></span></div><div class="line"> <span class="tag"><<span class="name">artifactId</span>></span>poi<span class="tag"></<span class="name">artifactId</span>></span></div><div class="line"> <span class="tag"><<span class="name">version</span>></span>3.9<span class="tag"></<span class="name">version</span>></span></div><div class="line"><span class="tag"></<span class="name">dependency</span>></span></div></pre></td></tr></table></figure>
<p>httpclient —> commons-codec(1.9)</p>
<p>poi —> commons-codec(1.5)</p>
<p>分析依赖后发现，maven选择了commons-codec(1.9)</p>
<p><a class="magnific-img" href="http://7xp2k4.com1.z0.glb.clouddn.com/WX20170620-102526.png"><img src="http://7xp2k4.com1.z0.glb.clouddn.com/WX20170620-102526.png" alt="" class="ui centered image"></a></p>
<h2 id="结论："><a href="#结论：" class="headerlink" title="结论："></a>结论：</h2><p>maven遇到依赖冲突后，主要两种原则解决：</p>
<p>1.路径优先原则：如第一个例子，</p>
<p>vips-common-cache —> vip-common-util —> commons-codec(1.6)</p>
<p>poi —> commons-codec(1.5)</p>
<p>commons-codec(1.6)路径深度是3， commons-codec(1.5)是2，所以maven选择较短路径的那个</p>
<p>2.声明优先原则：如第二个例子，当冲突依赖所处的路径相同，声明在前的会被引用</p>
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