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<a class="article-title" href="/2020/01/04/nginx/">nginx</a>
</h1>
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<div class="article-meta">
<a href="/2020/01/04/nginx/" class="article-date">
<time datetime="2020-01-04T09:40:34.000Z" itemprop="datePublished">2020-01-04</time>
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<h2 id="1-nginx是什么"><a href="#1-nginx是什么" class="headerlink" title="1.nginx是什么"></a>1.nginx是什么</h2><ul>
<li>Nginx是一款轻量级的Web服务器/反向代理服务器及电子邮件（IMAP/POP3）代理服务器。</li>
<li>因它的稳定性、丰富的功能集、实例配置文件和低系统资源的消耗而闻名。</li>
<li>其特点是占有内存少，并发能力强。</li>
</ul>
<h2 id="2-正向代理"><a href="#2-正向代理" class="headerlink" title="2.正向代理"></a>2.正向代理</h2><p>正向代理类似一个跳板机，代理访问外部资源。<br><img src="/img/nginx/nginx1.jpg" alt="a"></p>
<ul>
<li>总结来说：正向代理是一个位于客户端和原始服务器之间的服务器，为了从原始服务器取得内容，客户端向代理发送一个请求，并指定目标（原始服务器），然后代理向原始服务器转交请求并将获得的内容返回给客户端。客户端必须要进行一些特殊的设置才能使用正向代理。</li>
</ul>
<h2 id="3-正向代理的用途"><a href="#3-正向代理的用途" class="headerlink" title="3.正向代理的用途"></a>3.正向代理的用途</h2><ul>
<li>vpn</li>
<li>做缓存，加速访问资源</li>
<li>对客户端访问授权，上网进行认证</li>
<li>代理可以记录用户的访问记录（上网行为管理），对外隐藏用户信息</li>
</ul>
<h2 id="4-反向代理"><a href="#4-反向代理" class="headerlink" title="4.反向代理"></a>4.反向代理</h2><p>反向代理（Reverse Proxy）实际运行方式是指以代理服务器来接受网络上的连接请求，然后将请求转发给内部网络上的服务器，并将从服务器上的得到的结果返回给网络上请求连接的客户端，此时代理服务器对外就表现为一个服务器。<br><img src="/img/nginx/nginx2.jpg" alt="aa"></p>
<h2 id="5-反向代理的作用"><a href="#5-反向代理的作用" class="headerlink" title="5.反向代理的作用"></a>5.反向代理的作用</h2><ul>
<li>保证内网的安全，可以使用反向代理提供WAF功能，阻止web攻击。大型网站通常将反向代理作为公网访问地址，web服务器是内网。</li>
<li>负载均衡，通过反向代理服务器来优化网站的负载</li>
</ul>
<h2 id="6-为什么要使用代理服务器"><a href="#6-为什么要使用代理服务器" class="headerlink" title="6.为什么要使用代理服务器"></a>6.为什么要使用代理服务器</h2><ul>
<li><p>提高访问速度<br>由于目标主机返回的数据会存放在代理服务器的硬盘中，因此下一次客户再访问相同的站点数据时，会直接从代理服务器的硬盘中读取，起到了缓存的作用，尤其对于热门站点能明显提高请求速度。</p>
</li>
<li><p>防火墙作用<br>由于所有的客户机请求都必须通过代理服务器访问远程站点，因此可在代理服务器上设限，过滤某些不安全信息。</p>
</li>
<li><p>通过代理服务器访问不能访问的目标站点<br>互联网上有许多开发的代理服务器，客户机在访问受限时，可通过不受限的代理服务器访问目标站点，通俗说，我们使用的翻墙浏览器就是利用了代理服务器，虽然不能出国，但也可直接访问外网。</p>
</li>
</ul>
<h2 id="7-nginx代理配置文件"><a href="#7-nginx代理配置文件" class="headerlink" title="7.nginx代理配置文件"></a>7.nginx代理配置文件</h2><div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">server {</span><br><span class="line"> listen 80;</span><br><span class="line"> location / {</span><br><span class="line"> proxy_pass http://10.92.1.137:8080; <span class="comment"># 应用服务器HTTP地址</span></span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure></div>
<h2 id="8-nginx虚拟主机"><a href="#8-nginx虚拟主机" class="headerlink" title="8.nginx虚拟主机"></a>8.nginx虚拟主机</h2><p>在nginx上可以配置多个server，每个server即一个虚拟主机，当nginx接收到请求，获取该请求中的host请求头，将host值与多个server的server_name进行匹配，由匹配成功的那个server来处理请求，然后将请求转发到server中指定不同的服务器。不同的server可以指定不同的tomcat或其它服务器，由服务器来处理请求。当只有一个服务器，所有的请求转发到同一个端口；当有多个服务器时，这些服务器对应的监听不同的端口，则请求根据配置转发到指定的端口，虚拟主机的作用真正发挥。</p>
<h2 id="9-虚拟主机配置"><a href="#9-虚拟主机配置" class="headerlink" title="9.虚拟主机配置"></a>9.虚拟主机配置</h2><div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line">server {</span><br><span class="line"> listen 80;</span><br><span class="line"> server_name www.jnaw.com;</span><br><span class="line"> location / {</span><br><span class="line"> proxy_pass http://10.92.1.137:8080;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line">server {</span><br><span class="line"> listen 80;</span><br><span class="line"> server_name app.jnaw.com;</span><br><span class="line"> location / {</span><br><span class="line"> proxy_pass http://10.92.1.138:8080;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line">server {</span><br><span class="line"> listen 80;</span><br><span class="line"> server_name 7.7.9.138;</span><br><span class="line"> location / {</span><br><span class="line"> proxy_pass http://10.92.9.138:8080;</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure></div>
<h2 id="10-nginx负载均衡"><a href="#10-nginx负载均衡" class="headerlink" title="10.nginx负载均衡"></a>10.nginx负载均衡</h2><h3 id="优点"><a href="#优点" class="headerlink" title="优点"></a>优点</h3><ul>
<li>可以针对http应用做一些分流的策略，比如针对域名、目录结构，它的正则</li>
<li>规则比HAProxy更为强大和灵活</li>
<li>Nginx对网络稳定性的依赖非常小，理论上能ping通就就能进行负载功能</li>
<li>Nginx安装和配置比较简单，测试起来比较方便，它基本能把错误用日志打印出来</li>
<li>可以承担高负载压力且稳定，在硬件不差的情况下一般能支撑几万次的并发量</li>
<li>Nginx可以通过端口检测到服务器内部的故障，比如根据服务器处理网页返回的状态码、超时等等</li>
<li>Nginx不仅仅是一款优秀的负载均衡器/反向代理软件，它同时也是功能强大的Web应用服务器</li>
<li>Nginx现在作为Web反向加速缓存越来越成熟了，速度比传统的服务器更快</li>
<li>Nginx也可作为静态网页和图片服务器，这方面的性能也无对手</li>
</ul>
<h3 id="缺点"><a href="#缺点" class="headerlink" title="缺点"></a>缺点</h3><ul>
<li>Nginx仅能支持http、https和Email协议</li>
<li>对后端服务器的健康检查，只支持通过端口来检测，不支持通过url来检测</li>
<li>不支持Session的直接保持，但能通过ip_hash来解决</li>
</ul>
</div>
</div>
</article>
<article id="post-Linux常用命令" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/12/26/Linux常用命令/">Linux常用命令</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/12/26/Linux常用命令/" class="article-date">
<time datetime="2019-12-26T12:55:17.000Z" itemprop="datePublished">2019-12-26</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<h2 id="1-gpassword命令"><a href="#1-gpassword命令" class="headerlink" title="1.gpassword命令"></a>1.gpassword命令</h2><p>功能：管理组<br>用法：</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo gpasswd [-a user][-d user][-A user,...][-M user,...][-r][-R] groupname</span><br></pre></td></tr></table></figure></div>
<p>参数</p>
<ul>
<li>-a:添加到用户组</li>
<li>-d:从组删除</li>
<li>-A:指定管理员</li>
<li>-M:指定组成员和-A的用法差不多</li>
<li>-r:删除密码</li>
<li>-R:限制用户登入组，只有组内的成员才可以用newgrp加入该组</li>
</ul>
<p>示例：<br>将nginx加入到root组内</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo gpasswd -a nginx root</span><br></pre></td></tr></table></figure></div>
<h2 id="2-mkdir命令"><a href="#2-mkdir命令" class="headerlink" title="2.mkdir命令"></a>2.mkdir命令</h2><p>功能：创建目录<br>用法：</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo mkdir [参数] 目录</span><br></pre></td></tr></table></figure></div>
<p>参数：</p>
<ul>
<li>-m=mode 为目录指定访问权限，与chmod相似</li>
<li>-p 如果目录已经存在，则不会有错误提示。若父目录不存在，将会创建父目录。该选项常用于创建级联目录</li>
<li>-v 为每个目录显示提示信息</li>
</ul>
<p>示例：<br>创建级联目录。同一目录下的子目录放在大括号内用逗号隔开</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo mkdir -p baklog{bin,lib,<span class="built_in">log</span>/{cep,dod,testlog}}</span><br></pre></td></tr></table></figure></div>
<h2 id="3-文件权限"><a href="#3-文件权限" class="headerlink" title="3.文件权限"></a>3.文件权限</h2><p>linux系统文件夹644、755、777权限设置详情，左至右，第一位数字代表文件所有者的权限，第二位：同用户组用户的权限，第三位：其他用户的权限</p>
<ul>
<li>读取权限：4 r 表示；</li>
<li>写入—：2 w 表示；</li>
<li>执行—：1 x 表示；</li>
</ul>
<p>通过4、2、1的组合得到以下几种权限：</p>
<ul>
<li>0 （没有权限）</li>
<li>4 读取权限</li>
<li>5 4+1 读取+执行</li>
<li>6 4+2 读取+写入</li>
<li>7 4+2+1 读取+写入+执行</li>
</ul>
<p>以755为例</p>
<ul>
<li>所有者有读取、写入、执行权限</li>
<li>同用户组有读取、执行权限，但没有写入权限</li>
<li>同上</li>
</ul>
<h2 id="4-chmod命令"><a href="#4-chmod命令" class="headerlink" title="4.chmod命令"></a>4.chmod命令</h2><p>功能：修改文件权限<br>用法</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo chmod [-cfvr] [--<span class="built_in">help</span>][--version] mode file ...</span><br></pre></td></tr></table></figure></div>
<ul>
<li>u 表示该文件的拥有者，g 表示与该文件的拥有者属于同一个群体(group)者，o 表示其他以外的人，a 表示这三者皆是。</li>
<li>+ 表示增加权限、- 表示取消权限、= 表示唯一设定权限。</li>
<li>r 表示可读取，w 表示可写入，x 表示可执行，X 表示只有当该文件是个子目录或者该文件已经被设定过为可执行。</li>
<li>-c : 若该文件权限确实已经更改，才显示其更改动作</li>
<li>-f : 若该文件权限无法被更改也不要显示错误讯息</li>
<li>-v : 显示权限变更的详细资料</li>
<li>-R : 对目前目录下的所有文件与子目录进行相同的权限变更(即以递回的方式逐个变更)</li>
<li>–help : 显示辅助说明</li>
<li>–version : 显示版本</li>
</ul>
<p>示例：<br>将文件file1.txt 设置为所有人可读取</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">sudo chmod ugo+r file1.txt</span><br><span class="line">或</span><br><span class="line">chmod a+r file1.txt</span><br></pre></td></tr></table></figure></div>
<p>此外chmod也可以用数字来表示权限</p>
<p>语法：</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">chmod abc file</span><br></pre></td></tr></table></figure></div>
<p>其中a,b,c各为一个数字，分别表示User、Group、及Other的权限。 r=4，w=2，x=1</p>
<p>若要rwx属性则4+2+1=7；<br>若要rw-属性则4+2=6；<br>若要r-x属性则4+1=5。<br>以下两种写法，效果相同</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">chmod a=rwx file</span><br><span class="line">chmod 777 file</span><br></pre></td></tr></table></figure></div>
<h2 id="5-ln命令"><a href="#5-ln命令" class="headerlink" title="5.ln命令"></a>5.ln命令</h2><p>用法：</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo ln [参数][源文件或目录][目标文件或目录]</span><br></pre></td></tr></table></figure></div>
<p>参数：</p>
<ul>
<li>-b 删除，覆盖以前建立的链接</li>
<li>-d 允许超级用户制作目录的硬链接</li>
<li>-f 强制执行</li>
<li>-i 交互模式，文件存在则提示用户是否覆盖</li>
<li>-n 把符号链接视为一般目录</li>
<li>-s 软链接(符号链接)</li>
<li>-v 显示详细的处理过程</li>
</ul>
<p>示例：</p>
<p>创建软链接</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo ln -s /srv/http/uploaded /srv/docker/uploaded</span><br></pre></td></tr></table></figure></div>
</div>
</div>
</article>
<article id="post-服务器安装" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/12/26/服务器安装/">服务器安装</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/12/26/服务器安装/" class="article-date">
<time datetime="2019-12-26T03:54:17.000Z" itemprop="datePublished">2019-12-26</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<h2 id="1-系统更新"><a href="#1-系统更新" class="headerlink" title="1.系统更新"></a>1.系统更新</h2><ul>
<li>更新系统，升级系统包</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo yum update -y</span><br></pre></td></tr></table></figure></div>
<h2 id="2-用户"><a href="#2-用户" class="headerlink" title="2.用户"></a>2.用户</h2><ul>
<li>创建用户</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">adduser user_xxx</span><br></pre></td></tr></table></figure></div>
<ul>
<li>删除用户，及用户目录</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">userdel -r user_xxx</span><br></pre></td></tr></table></figure></div>
<ul>
<li>设置密码</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">passwd user_xxx</span><br></pre></td></tr></table></figure></div>
<ul>
<li>修改配置文件，添加sudo权限</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo visudo</span><br></pre></td></tr></table></figure></div>
<p>找到这一行 root ALL=(ALL) ALL，复制一行，然后将前面的用户名替换成需要修改的用户名，最后使用 Esc键 + :wq 保存并退出</p>
<h2 id="3-安装软件"><a href="#3-安装软件" class="headerlink" title="3.安装软件"></a>3.安装软件</h2><h3 id="3-1-docker"><a href="#3-1-docker" class="headerlink" title="3.1 docker"></a>3.1 docker</h3><ul>
<li>安装所需的软件包 yum-utils提供了yum-config-manager 效用，并device-mapper-persistent-data和lvm2由需要 devicemapper存储驱动程序。（楞恶心）</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo yum install -y yum-utils device-mapper-persistent-data lvm2</span><br></pre></td></tr></table></figure></div>
<ul>
<li>设置稳定版本库</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">sudo yum-config-manager \</span><br><span class="line"> --add-repo \</span><br><span class="line"> https://download.docker.com/linux/centos/docker-ce.repo</span><br></pre></td></tr></table></figure></div>
<ul>
<li>跟新yum包索引</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo yum makecache fast</span><br></pre></td></tr></table></figure></div>
<ul>
<li>安装docker-ce</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo yum install -y docker-ce</span><br></pre></td></tr></table></figure></div>
<ul>
<li>启动docker</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo systemctl start docker</span><br></pre></td></tr></table></figure></div>
<ul>
<li>查看当前安装版本,验证安装是否成功</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">docker --version</span><br></pre></td></tr></table></figure></div>
<ul>
<li>设置开机自启，重新启动服务</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">sudo systemctl <span class="built_in">enable</span> docker</span><br><span class="line"></span><br><span class="line">sudo systemctl restart docker</span><br></pre></td></tr></table></figure></div>
<h3 id="3-2-安装-git-zsh-nginx-nodejs-jdk-p7zip-htop"><a href="#3-2-安装-git-zsh-nginx-nodejs-jdk-p7zip-htop" class="headerlink" title="3.2 安装 git zsh nginx nodejs jdk p7zip htop"></a>3.2 安装 git zsh nginx nodejs jdk p7zip htop</h3><div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo yun install -y git zsh nginx nodejs java-1.8.0-openjdk-devel p7zip htop</span><br></pre></td></tr></table></figure></div>
<h3 id="3-3-docker-compose"><a href="#3-3-docker-compose" class="headerlink" title="3.3 docker-compose"></a>3.3 docker-compose</h3><div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo yum -y install docker-compose</span><br></pre></td></tr></table></figure></div>
<h3 id="3-4-Gradle"><a href="#3-4-Gradle" class="headerlink" title="3.4 Gradle"></a>3.4 Gradle</h3><ul>
<li>下载安装包</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">wget https://downloads.gradle.org/distributions/gradle-5.4.1-all.zip</span><br></pre></td></tr></table></figure></div>
<ul>
<li>解压缩到目录 /usr/software/</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">sudo mkdir /usr/software/</span><br><span class="line"><span class="built_in">cd</span> /usr/softwware/</span><br><span class="line">sudo 7za x ~/gradle-5.4.1-all.zip</span><br></pre></td></tr></table></figure></div>
<ul>
<li>打开环境变量</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo vim /etc/profile</span><br></pre></td></tr></table></figure></div>
<p>将下面代码复制到底部</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment"># gradle settings start 2019-05-27</span></span><br><span class="line"></span><br><span class="line">GRADLE_HOME=/usr/software/gradle-5.4.1</span><br><span class="line"><span class="built_in">export</span> PATH=<span class="variable">${GRADLE_HOME}</span>/bin:<span class="variable">${PATH}</span></span><br><span class="line"></span><br><span class="line"><span class="comment"># gradle settings end - 2019-05-27</span></span><br></pre></td></tr></table></figure></div>
<ul>
<li>重载这个文件</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="built_in">source</span> /etc/profile</span><br></pre></td></tr></table></figure></div>
<ul>
<li>检查安装</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">gradle -version</span><br></pre></td></tr></table></figure></div>
<h3 id="3-5-安装gulp"><a href="#3-5-安装gulp" class="headerlink" title="3.5 安装gulp"></a>3.5 安装gulp</h3><div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo npm i -g gulp</span><br></pre></td></tr></table></figure></div>
<h3 id="3-6-注意"><a href="#3-6-注意" class="headerlink" title="3.6 注意"></a>3.6 注意</h3><p>-新服务器要打开80端口</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">#查看80端口是否开放</span></span><br><span class="line">firewall-cmd --query-port=80/tcp</span><br><span class="line"></span><br><span class="line"><span class="comment">#打开80</span></span><br><span class="line">firewall-cmd --add-port=80/tcp</span><br><span class="line">firewall-cmd --zone=public --add-port=80/tcp --permanent</span><br></pre></td></tr></table></figure></div>
</div>
</div>
</article>
<article id="post-git仓库迁移" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/12/26/git仓库迁移/">git仓库迁移</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/12/26/git仓库迁移/" class="article-date">
<time datetime="2019-12-26T03:53:05.000Z" itemprop="datePublished">2019-12-26</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<h2 id="码云-Git-仓库迁移到-git-jnaw-top-服务器"><a href="#码云-Git-仓库迁移到-git-jnaw-top-服务器" class="headerlink" title="码云 Git 仓库迁移到 git.jnaw.top 服务器"></a>码云 Git 仓库迁移到 git.jnaw.top 服务器</h2><h2 id="公共账户"><a href="#公共账户" class="headerlink" title="公共账户"></a>公共账户</h2><ul>
<li>账户：git</li>
<li>密码：git</li>
</ul>
<h2 id="免密登录"><a href="#免密登录" class="headerlink" title="免密登录"></a>免密登录</h2><ul>
<li>先把自己电脑的公钥添加到 git 账户中</li>
<li><code>~/.ssh/authorized_keys</code> 【追加到此文件中】</li>
</ul>
<h2 id="以-ncp-项目为例迁移"><a href="#以-ncp-项目为例迁移" class="headerlink" title="以 ncp 项目为例迁移"></a>以 ncp 项目为例迁移</h2><ul>
<li>先在新的git服务器上创建一个空的项目ncp</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="built_in">cd</span> ~/cwbu/</span><br><span class="line">mkdir ncp</span><br><span class="line"><span class="built_in">cd</span> ncp</span><br><span class="line">git init --bare</span><br></pre></td></tr></table></figure></div>
<h2 id="克隆旧的仓库，推送到新的服务器"><a href="#克隆旧的仓库，推送到新的服务器" class="headerlink" title="克隆旧的仓库，推送到新的服务器"></a>克隆旧的仓库，推送到新的服务器</h2><ul>
<li>在本地 Git Bash 中执行命令</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">git <span class="built_in">clone</span> --bare [email protected]:allview-cwbu/ncp.git</span><br></pre></td></tr></table></figure></div>
<ul>
<li><code>[email protected]:allview-cwbu/ncp.git</code> 为原仓库地址</li>
<li>会生成一个文件夹：ncp.git</li>
<li>进入文件夹中</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="built_in">cd</span> ncp.git</span><br></pre></td></tr></table></figure></div>
<ul>
<li>推送到新的服务器</li>
</ul>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="SH"><figure class="iseeu highlight /sh"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">git push --mirror [email protected]:cwbu/ncp</span><br></pre></td></tr></table></figure></div>
<ul>
<li><code>[email protected]:cwbu/ncp</code> 为新的仓库地址</li>
</ul>
</div>
</div>
</article>
<article id="post-集群dockerswarm-cluster" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/11/06/集群dockerswarm-cluster/">集群dockerswarm/cluster</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/11/06/集群dockerswarm-cluster/" class="article-date">
<time datetime="2019-11-06T12:09:54.000Z" itemprop="datePublished">2019-11-06</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<p><img src="/img/cluster/note.jpg" alt></p>
</div>
</div>
</article>
<article id="post-G1学习" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/11/01/G1学习/">G1学习</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/11/01/G1学习/" class="article-date">
<time datetime="2019-11-01T07:53:07.000Z" itemprop="datePublished">2019-11-01</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
</div>
</div>
</article>
<article id="post-cms详解" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/11/01/cms详解/">CMS详解</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/11/01/cms详解/" class="article-date">
<time datetime="2019-11-01T07:43:34.000Z" itemprop="datePublished">2019-11-01</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<p>#CMS垃圾收集器</p>
<p>from ：<a href="http://www.mashibing.com" target="_blank" rel="noopener">www.mashibing.com</a></p>
<h2 id="目标："><a href="#目标：" class="headerlink" title="目标："></a>目标：</h2><p>获取最短的STW时间<br>为什么要STW？ 用户线程可能会修改对象的引用<br><a href="/img/jvm-cms/CMS.PDF">sad</a></p>
<h2 id="jvm内存模型"><a href="#jvm内存模型" class="headerlink" title="jvm内存模型"></a>jvm内存模型</h2><p><img src="/img/jvm-cms/jvm.jpg" alt></p>
<h2 id="常见的garbage-collection"><a href="#常见的garbage-collection" class="headerlink" title="常见的garbage collection"></a>常见的garbage collection</h2><p><img src="/img/jvm-cms/garbagecollection.png" alt></p>
<h3 id="各个GC之间的对比"><a href="#各个GC之间的对比" class="headerlink" title="各个GC之间的对比"></a>各个GC之间的对比</h3><p><img src="/img/jvm-cms/gc1.png" alt><br><img src="/img/jvm-cms/gc2.png" alt></p>
<p><img src="/img/jvm-cms/cms.png" alt><br><img src="/img/jvm-cms/cmsex.png" alt><br><img src="/img/jvm-cms/optimize1.png" alt><br><img src="/img/jvm-cms/optimize2.png" alt><br><img src="/img/jvm-cms/optimize3.png" alt></p>
</div>
</div>
</article>
<article id="post-hello-world" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/11/01/hello-world/">helloworld</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/11/01/hello-world/" class="article-date">
<time datetime="2019-11-01T02:31:41.000Z" itemprop="datePublished">2019-11-01</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<p><img src="/img/helloworld/mama.png" alt><br><img src="/img/helloworld/1.png" alt><br><img src="/img/helloworld/2.png" alt><br><img src="/img/helloworld/3.png" alt></p>
</div>
</div>
</article>
<article id="post-jenkins" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/11/01/jenkins/">jenkins 搭建</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/11/01/jenkins/" class="article-date">
<time datetime="2019-11-01T02:31:41.000Z" itemprop="datePublished">2019-11-01</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<h1 id="jenkins-搭建"><a href="#jenkins-搭建" class="headerlink" title="jenkins 搭建"></a>jenkins 搭建</h1><p><img src="/img/jenkins/jenkins.png" alt></p>
<h1 id="Problem"><a href="#Problem" class="headerlink" title="Problem:"></a>Problem:</h1><ol>
<li>centOS服务器上部署遇到插件版本缺失的问题，可以去下面网址下载再手动上传插件 <a href="http://updates.jenkins-ci.org/download/plugins/" target="_blank" rel="noopener">http://updates.jenkins-ci.org/download/plugins/</a></li>
<li>配置gradle 构建的时候，在高级中可以设置配置的路径<br>${workspace}/backstage_management/backend</li>
</ol>
</div>
</div>
</article>
<article id="post-GC and Tuning" class="article global-container article-type-post" itemscope itemprop="blogPost">
<header class="article-header">
<h1 itemprop="name">
<a class="article-title" href="/2019/10/29/GC and Tuning/">jvm调优实践</a>
</h1>
</header>
<div class="article-meta">
<a href="/2019/10/29/GC and Tuning/" class="article-date">
<time datetime="2019-10-29T07:52:41.407Z" itemprop="datePublished">2019-10-29</time>
</a>
</div>
<div class="article-inner">
<div class="article-content article-content-cloud" itemprop="articleBody">
<h1 id="GC和GC-Tuning"><a href="#GC和GC-Tuning" class="headerlink" title="GC和GC Tuning"></a>GC和GC Tuning</h1><h3 id="GC的基础知识"><a href="#GC的基础知识" class="headerlink" title="GC的基础知识"></a>GC的基础知识</h3><p><img src="/img/jvmtuning/jvm1.png" alt><br><img src="/img/jvmtuning/jvm2.png" alt></p>
<p>Jdk 11 zgc 10ms （垃圾收集器的停顿时间）<br>Azul zing 1ms 收费 c4</p>
<p>• -Xms:初始堆大小<br>• -Xmx:最大堆大小<br>• xmn新生代大小</p>
<h4 id="1-什么是垃圾"><a href="#1-什么是垃圾" class="headerlink" title="1.什么是垃圾"></a>1.什么是垃圾</h4><p>· C语言申请内存：malloc free<br>·<br>· C++： new delete<br>·<br>· c/c++需要手动回收内存<br>·<br>· Java: new ？<br>·<br>· 自动内存回收，编程上简单，系统不容易出错，手动释放内存，容易出两种类型的问题：<br>·<br>· 1. 忘记回收<br>· 2. 多次回收</p>
<p>没有任何引用指向的一个对象或者循环引用多个对象 —– 垃圾</p>
<h4 id="2-如何定位垃圾"><a href="#2-如何定位垃圾" class="headerlink" title="2.如何定位垃圾"></a>2.如何定位垃圾</h4><ol>
<li>引用计数 reference count （不能解决循环引用的问题）</li>
<li>根可达算法 通过根对象能够链接到的 <img src="/img/jvmtuning/GCRoots.png" alt></li>
</ol>
<h4 id="3-常见的垃圾回收算法"><a href="#3-常见的垃圾回收算法" class="headerlink" title="3.常见的垃圾回收算法"></a>3.常见的垃圾回收算法</h4><ol>
<li>标记清除 Mark Sweep - 两边扫描，效率偏低，位置不连续 产生内存碎片化 适用存活对象较多的情况<img src="/img/jvmtuning/MSALG.png" alt></li>
<li>拷贝算法 Copy - 没有碎片，浪费空间 <img src="/img/jvmtuning/copyalg.png" alt></li>
<li>标记压缩 Mark Compact- 没有碎片，效率偏低(两边扫描，指针需要调整)<img src="/img/jvmtuning/MCALG.png" alt></li>
</ol>
<h4 id="4-JVM内存分代模型（用于分代垃圾回收算法）"><a href="#4-JVM内存分代模型（用于分代垃圾回收算法）" class="headerlink" title="4.JVM内存分代模型（用于分代垃圾回收算法）"></a>4.JVM内存分代模型（用于分代垃圾回收算法）</h4><p><img src="/img/jvmtuning/HEAPS.png" alt><br><img src="/img/jvmtuning/objectnew-dead.png" alt></p>
<ol>
<li>部分垃圾回收器使用的模型</li>
<li>新生代 + 老年代 + 永久代（1.7）/ 元数据区(1.8) Metaspace<ol>
<li>永久代 元数据 - Class</li>
<li>永久代必须指定大小限制 ，元数据可以设置，也可以不设置，无上限（受限于物理内存）</li>
<li>字符串常量 1.7 - 永久代，1.8 - 堆</li>
<li>MethodArea逻辑概念 - 永久代、元数据</li>
</ol>
</li>
<li>新生代 = Eden + 2个suvivor区 <ol>
<li>YGC回收之后，大多数的对象会被回收，活着的进入s0</li>
<li>再次YGC，活着的对象eden + s0 -> s1</li>
<li>再次YGC，eden + s1 -> s0</li>
<li>年龄足够 -> 老年代 （15 CMS 6）</li>
<li>s区装不下 -> 老年代</li>
</ol>
</li>
<li>老年代<ol>
<li>顽固分子</li>
<li>老年代满了FGC Full GC</li>
</ol>
</li>
<li>GC Tuning (Generation)<ol>
<li>尽量减少FGC</li>
<li>MinorGC = YGC</li>
<li>MajorGC = FGC</li>
</ol>
</li>
</ol>
<h4 id="5-常见的垃圾回收器-（所有的都会产生stw）"><a href="#5-常见的垃圾回收器-（所有的都会产生stw）" class="headerlink" title="5.常见的垃圾回收器 （所有的都会产生stw）"></a>5.常见的垃圾回收器 （所有的都会产生stw）</h4><p><img src="/img/jvmtuning/GC.png" alt></p>
<ol>
<li>Serial 年轻代 串行回收 单线程 会产生STW ，找到一个safe point （安全点）执行gc</li>
<li>Parallel Scavenge 年轻代 并行回收 有STW 吞吐量优先 </li>
<li>ParNew 年轻代 为了和配合CMS的并行回收 响应时间优先</li>
<li>SerialOld 单线程</li>
<li>ParallelOld</li>
<li>ConcurrentMarkSweep 老年代 并发的， 垃圾回收和应用程序同时运行，降低STW的时间(200ms) <img src="/img/jvmtuning/CMS.png" alt></li>
<li>G1(10ms)</li>
<li>ZGC (1ms) PK C++</li>
<li>Shenandoah</li>
<li>Eplison</li>
</ol>
<p>1.8默认的垃圾回收：PS + ParallelOld<br><img src="/img/jvmtuning/PN-PS.png" alt></p>
<h4 id="6-JVM调优第一步，了解生产环境下的垃圾回收器组合"><a href="#6-JVM调优第一步，了解生产环境下的垃圾回收器组合" class="headerlink" title="6.JVM调优第一步，了解生产环境下的垃圾回收器组合"></a>6.JVM调优第一步，了解生产环境下的垃圾回收器组合</h4><ul>
<li><p>JVM的命令行参数参考：<a href="https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html" target="_blank" rel="noopener">https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html</a></p>
</li>
<li><p>HotSpot参数分类<br> java -X</p>
<ol>
<li><p>标准： - 开头，所有的HotSpot都支持</p>
</li>
<li><p>非标准：-X 开头，特定版本HotSpot支持特定命令</p>
</li>
<li><p>不稳定：-XX 开头，下个版本可能取消</p>
</li>
</ol>
</li>
<li><p>测试代码</p>
<div class="highlight-box"autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" contenteditable="true"data-rel="PLAIN"><figure class="iseeu highlight /plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">sout(hellogc)</span><br><span class="line">list </span><br><span class="line">for(){</span><br><span class="line"> byte [] = new byte[1024*1024]</span><br><span class="line"> list.add</span><br><span class="line">}</span><br></pre></td></tr></table></figure></div>
<ol>
<li><p>java -XX:+PrintCommandLineFlags HelloGC</p>
</li>
<li><p>java -Xmn 10M -Xms 10M -Xmx 40M -XX:+PrintCommandLineFlags HelloGC<br>java -XX:PrintGCDetails -Xms 10M Xmx 10M</p>
</li>
<li><p>-XX:+PrintFlagsFinal 最终参数值</p>
</li>
<li><p>-XX:+PrintFlagsInitial 默认参数值<br>java -XX:+PrintFlagsFinal | wc -l 统计结果有多少行</p>
</li>
<li><p>java -XX:+UseConcMarkSweepGC [文件名] 指定GC</p>
</li>
<li><p>java -XX:+PrintFlagsFinal -version | grep SerialGC 在查询得结果中搜索 ‘SerialGC’</p>
</li>
</ol>
</li>
</ul>
<ul>
<li><p>常见得垃圾回收器组合(1,8)</p>
<ol>
<li><p>-XX:+UseSerialGC = Serial New(DefNew) +Serial Old</p>
</li>
<li><p>-XX:UseParNewGC = ParNew + SerialOld<br>这个组合已经很少用，（在某些版本已经废弃）</p>
</li>
<li><p>UseConc<font color="red">(urrent)</font>MarkSweepGC = ParNew + CMS + SerialOld<br>老年代用标记清除长时间产生大量碎片化，会触发一次SerialOld得FGC,如果内存特别大得话会很慢.<br>使用CMS一定要避免频繁得FGC</p>
</li>
<li><p>UseParallelGC = Parallel Scavenge + Parallel Old <font color="red">(1.8默认)</font><br>[PS+SerialOld]</p>
</li>
<li><p>UseParallelOldGC = Parallel Scavenge + Parallel Old</p>
</li>
<li><p>UseG1GC</p>
</li>
</ol>
</li>
</ul>
<h4 id="7-调优-从规划开始"><a href="#7-调优-从规划开始" class="headerlink" title="7.调优 从规划开始"></a>7.调优 从规划开始</h4><p><img src="/img/jvmtuning/example1.png" alt><br>一台机器也可以干这个事，把eden区设大 ，慢慢处理，只要不触发ygc就ok，之不过这样的风险比较大</p>
<ul>
<li><p>调优，从业务场景开始，没有业务场景得调优是耍流氓</p>
</li>
<li><p>无监控，不调优</p>
</li>
<li><p>步骤：</p>
<ol>
<li>熟悉业务场景（没有最好的垃圾回收器，只有最合适的）<ol>
<li>响应时间、停顿时间</li>
<li>吞吐量 = 用户时间/用户时间+GC时间</li>
</ol>
</li>
<li>选择回收器组合</li>
<li>计算内存需求</li>
<li>设定年代大小，升级年龄</li>
<li>设定日志参数<br> java -Xloggc:/root/gc-%t.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLofFileSize=20M -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCCsuse (jdk9(包含)之后不再好用， 去除了UseGCLogFileRotation这个参数)<br> 1.9开始参考下文<br>java -Xlog:gc:file=gctrace.txt<font color="red"><strong>::</strong></font> filecount=5,filesize=1M<br> <a href="https://docs.oracle.com/javase/10/tools/java.htm#JSWOR-GUID-BE93ABDC-999C-4CB5-A88B-1994AAAC74D5" target="_blank" rel="noopener">https://docs.oracle.com/javase/10/tools/java.htm#JSWOR-GUID-BE93ABDC-999C-4CB5-A88B-1994AAAC74D5</a></li>
<li>观察日志情况<br>java -XX:PrintGCDetails -Xms 10M Xmx 10M<br><img src="/img/jvmtuning/logsdetail.png" alt><br><img src="/img/jvmtuning/logs2.png" alt></li>
</ol>
<p><img src="/img/jvmtuning/loggc.png" alt></p>
<p> 小问题：Linux下使用的垃圾回收器的版本看不出来<br> 1.8.0_181 看不出来 copy + mark compact<br> 1.8.0_222 默认 ps + po</p>
<p> 调优 跟使用的jdk版本有巨大的关系</p>
</li>
</ul>
<h4 id="8-实战操作"><a href="#8-实战操作" class="headerlink" title="8.实战操作"></a>8.实战操作</h4><ol>
<li>top 命令观察问题，看那个进程占用cpu和memory居高不下</li>
<li>jps 定位具体java进程</li>
<li>动态观察<br>jmap -histo pid 查看这个进程中对象占用内存情况<br>jstat -gc<br>Arthas 阿里分析工具<br>jmx<br>阅读gc日志发现频繁jc</li>
<li>导出dump文件<br>java -Xms 20M -Xmx 20M -XX:+HeapDumpOnOutOfMemoryError .java （死了以后会导出文件）<br>jmap -dumpL:format=b,file =aaa.dump pid 慎用 ，内存已经很大的情况下再执行这个可能会导致宕机</li>
<li>使用MAT/jhat分析文件 jhat aaa.dump <h3 id="参考资料"><a href="#参考资料" class="headerlink" title="参考资料"></a>参考资料</h3></li>
</ol>
<ol>
<li><a href="https://blogs.oracle.com/jonthecollector/our-collectors" target="_blank" rel="noopener">https://blogs.oracle.com/jonthecollector/our-collector</a></li>
<li><a href="https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html" target="_blank" rel="noopener">https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html</a></li>
<li><a href="http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp" target="_blank" rel="noopener">http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp</a></li>
</ol>
<h3 id="习题"><a href="#习题" class="headerlink" title="习题"></a>习题</h3><p><img src="/img/jvmtuning/task1.png" alt><br><img src="/img/jvmtuning/task2.png" alt></p>
</div>
</div>
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