Tomcat - Tomcat 8.5.55 启动过程源码分析阶段三_start阶段

怼烎@ 2023-02-14 02:42 22阅读 0赞

### 文章目录 ###

*  启动流程分析
 *  Pre
 *  Star阶段
 *   *  start总览
     *  start源码分析
     *   *  StandardServer Start
         *  StandardService Start
         *   *  StandardEngine Start
             *  Connector Start
 *  小结

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# 启动流程分析 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 1]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 2]

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# Pre #

[Tomcat - Tomcat 8.5.55 启动过程源码分析阶段二\_load加载初始化][Tomcat - Tomcat 8.5.55 _load]

说完了load阶段，这里我们继续来看下最后一个start阶段

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# Star阶段 #

## start总览 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 3]

你会发现和 load阶段非常相似

这里我们就不展开的这么详细了，梳理核心脉络~

--------------------

## start源码分析 ##

Bootstrap\#main -----> daemon.start(); -------反射调用-------> Catalina \# start -------------> getServer().start(); -------模板方法LifeCycleBase--------> startInternal();

还是模板模式

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 4]

### StandardServer Start ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 5]

这里主要是继续启动Service

### StandardService Start ###

还是会走到生命周期里 ，统一收到LifeCycle接口定义的生命周期管理 抽象类LifeCycleBase ，子类重写startInternal()

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 6]  
一样的套路

精简后的核心代码如下：

@Override
        protected void startInternal() throws LifecycleException { 
    
           
            // Start our defined Container first
            if (engine != null) { 
                synchronized (engine) { 
                    engine.start();
                }
            }
     
      
            // Start our defined Connectors second
            synchronized (connectorsLock) { 
                for (Connector connector: connectors) { 
                      connector.start();
                }
            }
        }

分两大块

*  engine.start()
 *  connector.start()

接下来逐一分析

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#### StandardEngine Start ####

大致流程一览  
StandardEngine \# startInternal ---------> 调用父类ContainerBase\#startInternal ---------> startStopExecutor 将子容器Host提交到具体的StartChild线程类并行执行 —> … 使用**事件驱动** 初始化 Servlet

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仔细看看吧

继续 LifeCycleBase \# startInternal();

调用 StandardEngine

![在这里插入图片描述][20200531172006416.png]

@Override
        protected synchronized void startInternal() throws LifecycleException { 
    
            
            // Standard container startup
            super.startInternal();
        }

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父类 ContainerBase \# startInternal 的方法

看下调用栈 也能看出  
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跟进去 关键代码

结合Server.xml配置文件 Engine节点信息

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// 查找子容器，启动子容器 
    
    // Start our child containers, if any
     Container children[] = findChildren();
    	 List<Future<Void>> results = new ArrayList<>();
    	 for (Container child : children) { 
    	     results.add(startStopExecutor.submit(new StartChild(child)));
     }

![在这里插入图片描述][2020060114315256.png]  
children事实上就是Host的集合， 然后 startStopExecutor 提交启动任务 ，这个startStopExecutor就是在load节点初始化好的，这里来使用。

那就看 StartChild 线程呗

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继续走

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 12]

跟进去 还是 LifyCycleBean --> StandardHost \# startInternal -----> super.startInternal(); ----> setState(LifecycleState.STARTING);

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设置生命周期 触发实例化Context —> LifyCycleBean \# setStateInternal -----> fireLifecycleEvent(lifecycleEvent, data);

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 14]

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触发Host的生命周期事件后，将后续工作交给生命周期监听器HostConfig来进行,Hostconfig\#lifecycleEvent方法,捕获start事件，执行start方法

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 17]

紧接着就是下面的流程了

\-------> Hostconfig\#deployApps--------------> Hostconfig\#deployDirectories ,以线程方式并行处理多个项目 ---------> DeployDirectory 线程类 ------>Hostconfig\#deployDirectory-----------------------> 通过xml解析对象进行分析,设置一些context应用的必要属性 ，在addChild方法中完善context的过程 -------> ContainerBase\#addChild方法--------------> ContainerBase\#addChildInternal---------> StandardContext\#startInternal方法 ------------> 给每个应用设置类加载器 ,把具体每个应用的处理交给了ContextConfig . loadOnStartup方法根据web.xml中配置servlet的load-on-startup来进行创建实例化对应servlet。执行之后，instance就有具体对象了。 ------> StandardContext\#loadOnStartup方法 ------> StandardWrapper\#load方法 ---------------------> StandardWrapper\#loadServlet方法

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#### Connector Start ####

主要流程

Connector\# startInternal ------> AbstractProtocol\# start -----------> AbstractEndpoint \# start ----------> NioEndpoint\# startInternal ----------> AbstractEndpoint\#startAcceptorThreads ------> NioEndpoint\# createAcceptor -------> Acceptor线程\#run方法 Socket.Accept

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# 小结 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70 18]

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[Tomcat - Tomcat 8.5.55 _load]: https://artisan.blog.csdn.net/article/details/106439395
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