tomcat线程初探
Posted handsomecui
tags:
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博主：handsomecui，希望路过的各位大佬留下你们宝贵的意见，在这里祝大家冬至快乐。
缘由：
初探缘由，在业务层想要通过（当前线程的栈）来获取到控制层的类名，然后打日志，可是发现并不能通过当前线程获取到控制层的类，两者并没有在一个线程内，进而引发了我对这一问题的思考。
解决步骤：
一. 我先打印出了当前运行的所有线程的名字以及栈的运行情况：
Thread list size == 21 线程名：main java.net.PlainSocketImpl:socketAccept java.net.AbstractPlainSocketImpl:accept java.net.ServerSocket:implAccept java.net.ServerSocket:accept org.apache.catalina.core.StandardServer:await org.apache.catalina.startup.Catalina:await org.apache.catalina.startup.Catalina:start sun.reflect.NativeMethodAccessorImpl:invoke0 sun.reflect.NativeMethodAccessorImpl:invoke sun.reflect.DelegatingMethodAccessorImpl:invoke java.lang.reflect.Method:invoke org.apache.catalina.startup.Bootstrap:start org.apache.catalina.startup.Bootstrap:main 线程名：ContainerBackgroundProcessor[StandardEngine[Catalina]] java.io.UnixFileSystem:list java.io.File:list org.apache.catalina.startup.HostConfig:deployApps org.apache.catalina.startup.HostConfig:check org.apache.catalina.startup.HostConfig:lifecycleEvent org.apache.catalina.util.LifecycleSupport:fireLifecycleEvent org.apache.catalina.util.LifecycleBase:fireLifecycleEvent org.apache.catalina.core.ContainerBase:backgroundProcess org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor:processChildren org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor:processChildren org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor:run java.lang.Thread:run 线程名：http-bio-8080-Acceptor-0 java.net.PlainSocketImpl:socketAccept java.net.AbstractPlainSocketImpl:accept java.net.ServerSocket:implAccept java.net.ServerSocket:accept org.apache.tomcat.util.net.DefaultServerSocketFactory:acceptSocket org.apache.tomcat.util.net.JIoEndpoint$Acceptor:run java.lang.Thread:run 线程名：http-bio-8080-AsyncTimeout java.lang.Thread:sleep org.apache.tomcat.util.net.JIoEndpoint$AsyncTimeout:run java.lang.Thread:run 线程名：ajp-bio-8009-Acceptor-0 java.net.PlainSocketImpl:socketAccept java.net.AbstractPlainSocketImpl:accept java.net.ServerSocket:implAccept java.net.ServerSocket:accept org.apache.tomcat.util.net.DefaultServerSocketFactory:acceptSocket org.apache.tomcat.util.net.JIoEndpoint$Acceptor:run java.lang.Thread:run 线程名：ajp-bio-8009-AsyncTimeout java.lang.Thread:sleep org.apache.tomcat.util.net.JIoEndpoint$AsyncTimeout:run java.lang.Thread:run 线程名：http-bio-8080-exec-1 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-2 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-3 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-4 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-5 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-6 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-7 java.lang.Thread:getStackTrace com.thor.dao.domain.common.util.CommonUtil:getThreadGroup com.thor.service.customer.CustomerService:post com.thor.service.customer.CustomerService$$FastClassByCGLIB$$9a694ea:invoke net.sf.cglib.proxy.MethodProxy:invoke org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation:invokeJoinpoint org.springframework.aop.framework.ReflectiveMethodInvocation:proceed org.springframework.transaction.interceptor.TransactionInterceptor:invoke org.springframework.aop.framework.ReflectiveMethodInvocation:proceed org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor:intercept com.thor.service.customer.CustomerService$$EnhancerByCGLIB$$898851cc:post com.thor.control.customer.CustomControl:post sun.reflect.NativeMethodAccessorImpl:invoke0 sun.reflect.NativeMethodAccessorImpl:invoke sun.reflect.DelegatingMethodAccessorImpl:invoke java.lang.reflect.Method:invoke org.springframework.web.method.support.InvocableHandlerMethod:invoke org.springframework.web.method.support.InvocableHandlerMethod:invokeForRequest org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod:invokeAndHandle org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter:invokeHandlerMethod org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter:handleInternal org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter:handle org.springframework.web.servlet.DispatcherServlet:doDispatch org.springframework.web.servlet.DispatcherServlet:doService org.springframework.web.servlet.FrameworkServlet:processRequest org.springframework.web.servlet.FrameworkServlet:doPost javax.servlet.http.HttpServlet:service javax.servlet.http.HttpServlet:service org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter org.apache.tomcat.websocket.server.WsFilter:doFilter org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter com.thor.control.user.web.filter.AuthFilter:doFilterInternal com.taovip.login.session.auth.BaseFilter:doFilter org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter com.thor.control.user.web.filter.LogFilter:doFilter org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter com.taovip.login.session.client.ClientSessionFilter:doFilter org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter com.thor.control.user.web.filter.LoginFilter:doFilter org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter org.springframework.web.filter.CharacterEncodingFilter:doFilterInternal org.springframework.web.filter.OncePerRequestFilter:doFilter org.apache.catalina.core.ApplicationFilterChain:internalDoFilter org.apache.catalina.core.ApplicationFilterChain:doFilter org.apache.catalina.core.StandardWrapperValve:invoke org.apache.catalina.core.StandardContextValve:invoke org.apache.catalina.authenticator.AuthenticatorBase:invoke org.apache.catalina.core.StandardHostValve:invoke org.apache.catalina.valves.ErrorReportValve:invoke org.apache.catalina.valves.AccessLogValve:invoke org.apache.catalina.core.StandardEngineValve:invoke org.apache.catalina.connector.CoyoteAdapter:service org.apache.coyote.http11.AbstractHttp11Processor:process org.apache.coyote.AbstractProtocol$AbstractConnectionHandler:process org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor:run java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-8 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-9 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：http-bio-8080-exec-10 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:park java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject:await java.util.concurrent.LinkedBlockingQueue:take org.apache.tomcat.util.threads.TaskQueue:take org.apache.tomcat.util.threads.TaskQueue:take java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run org.apache.tomcat.util.threads.TaskThread$WrappingRunnable:run java.lang.Thread:run 线程名：mergeAppender java.lang.Object:wait java.lang.Object:wait org.apache.log4j.AsyncAppender$Dispatcher:run java.lang.Thread:run 线程名：alertAppender java.lang.Object:wait java.lang.Object:wait org.apache.log4j.AsyncAppender$Dispatcher:run java.lang.Thread:run 线程名：Timer-0 java.lang.Object:wait java.util.TimerThread:mainLoop java.util.TimerThread:run 线程名：pool-7-thread-1 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:parkNanos java.util.concurrent.SynchronousQueue$TransferStack:awaitFulfill java.util.concurrent.SynchronousQueue$TransferStack:transfer java.util.concurrent.SynchronousQueue:poll java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run java.lang.Thread:run 线程名：pool-7-thread-2 sun.misc.Unsafe:park java.util.concurrent.locks.LockSupport:parkNanos java.util.concurrent.SynchronousQueue$TransferStack:awaitFulfill java.util.concurrent.SynchronousQueue$TransferStack:transfer java.util.concurrent.SynchronousQueue:poll java.util.concurrent.ThreadPoolExecutor:getTask java.util.concurrent.ThreadPoolExecutor:runWorker java.util.concurrent.ThreadPoolExecutor$Worker:run java.lang.Thread:run
代码：
ThreadGroup threadGroup = Thread.currentThread().getThreadGroup(); int estimatedSize = threadGroup.activeCount() * 2; Thread[] slackList = new Thread[estimatedSize]; // 获取根线程组的所有线程 int actualSize = threadGroup.enumerate(slackList); // copy into a list that is the exact size Thread[] list = new Thread[actualSize]; System.arraycopy(slackList, 0, list, 0, actualSize); System.out.println("Thread list size == " + list.length); for (Thread thread : list) { System.out.println("线程名：" + thread.getName()); StackTraceElement[] stackTrace = thread.getStackTrace(); for(StackTraceElement e : stackTrace){ System.out.println(e.getClassName()+":"+e.getMethodName()); } }
所以看到了这么多线程，网上搜了好多，都看不懂，终于找到了一篇只讲名功能的博客：https://www.cnblogs.com/dhcn/p/7120713.html
Work线程
功能
HTTP请求的处理线程(非NIO)。当有新的http请求进来后，则会从线程池中获得一个线程Work对象，调用Work.assign函数，将新到的http请求分配给这个线程。
名称
名称是http-[IpAddr]-[Port]-[Number]，如http-0.0.0.0-8080-1
这个可以从Http11Protocol中的setName函数和Worker中的start方法得知这个命名方式。
| 1 | public String getName() { |
| 2 | String encodedAddr = ""; |
| 3 | if (getAddress() != null) { |
| 4 | encodedAddr = "" + getAddress(); |
| 5 | if (encodedAddr.startsWith("/" )) |
| 6 | encodedAddr = encodedAddr.substring(1); |
| 7 | encodedAddr = URLEncoder. encode(encodedAddr) + "-"; |
| 8 | } |
| 9 | |
| 10 | return ("http-" + encodedAddr + endpoint.getPort()); |
| 11 | } |
| 12 | |
| 13 |
线程类：JIoEndpoint.Work
在JIoEndpoint.Work的run方法中调用await方法等待并获得下一个socket，传给handle进行处理。在await方法中，如果没有分配新的客户端请求socket， available变量会一直false，并会循环调用wait方法阻塞自己，同时释放Work对象的锁，直到Acceptor线程获得新的socket， 并调用Work.assign方法分配给该工作线程。 这时availble变量才为设置为true，并且await方法会返回分配的socket对象。
| 1 | protected class Worker implements Runnable { |
| 2 | |
| 3 | protected Thread thread = null; |
| 4 | |
| 5 | protected boolean available = false; |
| 6 | |
| 7 | protected Socket socket = null; |
| 8 | |
| 9 | /** |
| 10 | |
| 11 | * Process an incoming TCP/IP connection on the specified socket. Any |
| 12 | |
| 13 | * exception that occurs during processing must be logged and swallowed. |
| 14 | |
| 15 | * <b>NOTE</b> : This method is called from our Connector\'s thread. We |
| 16 | |
| 17 | * must assign it to our own thread so that multiple simultaneous |
| 18 | |
| 19 | * requests can be handled. |
| 20 | |
| 21 | * |
| 22 | |
| 23 | * @param socket TCP socket to process |
| 24 | |
| 25 | */ |
| 26 | |
| 27 | synchronized void assign(Socket socket ) { |
| 28 | |
| 29 | // Wait for the Processor to get the previous Socket |
| 30 | |
| 31 | while (available ) { |
| 32 | |
| 33 | try { |
| 34 | |
| 35 | wait(); |
| 36 | |
| 37 | } catch (InterruptedException e) { |
| 38 | |
| 39 | } |
| 40 | |
| 41 | } |
| 42 | |
| 43 | // Store the newly available Socket and notify our thread |
| 44 | |
| 45 | this.socket = socket ; |
| 46 | |
| 47 | available = true ; |
| 48 | |
| 49 | notifyAll(); |
| 50 | |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | |
| 55 | * 等待新分配的Socket |
| 56 | |
| 57 | */ |
| 58 | |
| 59 | private synchronized Socket await() { |
| 60 | |
| 61 | //等待Connector提供新的Socket |
| 62 | |
| 63 | while (!available ) { |
| 64 | |
| 65 | try { |
| 66 | |
| 67 | wait(); |
| 68 | |
| 69 | } catch (InterruptedException e) { |
| 70 | |
| 71 | } |
| 72 | |
| 73 | } |
| 74 | |
| 75 | //通知Connector我们已经接收到这个Socket |
| 76 | |
| 77 | Socket socket = this.socket ; |
| 78 | |
| 79 | available = false ; |
| 80 | |
| 81 | notifyAll(); |
| 82 | |
| 83 | return (socket); |
| 84 | |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | |
| 89 | * 后台线程，监听进入的TCP/IP连接，并传递给合适的处理模块 |
| 90 | |
| 91 | */ |
| 92 | |
| 93 | public void run() { |
| 94 | |
| 95 | // Process requests until we receive a shutdown signal |
| 96 | |
| 97 | //处理请求直到我们接收到shutdown信号 |
| 98 | |
| 99 | while (running ) { |
| 100 | |
| 101 | //等待下一个分配的socket |
| 102 | |
| 103 | Socket socket = await(); |
| 104 | |
| 105 | if (socket == null) |
| 106 | |
| 107 | continue; |
| 108 | |
| 109 | //设置socket的选项，并处理socket |
| 110 | |
| 111 | if (!setSocketOptions(socket) || !handler.process(socket)) { |
| 112 | |
| 113 | // 关闭socket |
| 114 | |
| 115 | try { |
| 116 | |
| 117 | socket.close(); |
| 118 | |
| 119 | } catch (IOException e) { |
| 120 | |
| 121 | } |
| 122 | |
| 123 | } |
| 124 | |
| 125 | // Finish up this request |
| 126 | |
| 127 | socket = null; |
| 128 | |
| 129 | //回收线程 |
| 130 | |
| 131 | recycleWorkerThread( this); |
| 132 | |
| 133 | } |
| 134 | |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | |
| 139 | * 开启后台处理线程 |
| 140 | |
| 141 | */ |
| 142 | |
| 143 | public void start() { |
| 144 | |
| 145 | thread = new Thread(this); |
| 146 | |
| 147 | thread.setName(getName() + "-" + (++curThreads)); |
| 148 | |
| 149 | thread.setDaemon(true); |
| 150 | |
| 151 | thread.start(); |
| 152 | |
| 153 | } |
| 154 | |
| 155 | } |
| 156 | |
| 157 |
所属线程池
所属线程池实现功能比较简单，是内嵌到JIoEndpoint类中的实现。基本数据结构是一个工作线程栈JIoEndpoint.WorkerStack。
线程池主要属性
curThreadsBusy：当前繁忙线程数
curThreads:当前工作线程数
maxThreads:最大工作线程数
线程池启动
这个线程池实现功能比较简单，不需要太多启动功能。可以从JIoEndpoint类的start方法看到，启动初始化需要做的事是分配线程栈worker空间。
任务分配时序图
任务分配
通过JIoEndPoint中createWorkerThread方法获得一个工作线程。如在工作线程栈workers中获得一个线程对象，如果线程栈已经是空的，并且当前线程数量curThreads还小于最大线程数maxThreads，那么就创建一个新的工作线程。然后调用Work.assign方法分配给工作线程。
| 1 | protected Worker createWorkerThread() { |
| 2 | |
| 3 | //获得工作线程栈workers的锁 |
| 4 | |
| 5 | synchronized (workers ) { |
| 6 | |
| 7 | //如果工作线程栈里有线程则返回栈顶工作线程 |
| 8 | |
| 9 | if (workers .size() > 0) { |
| 10 | |
| 11 | curThreadsBusy++; |
| 12 | |
| 13 | return workers .pop(); |
| 14 | |
| 15 | } |
| 16 | |
| 17 | //如果工作线程栈里没有线程，maxThreads大于0且当前线程数小于最大线程数，则创建一个新的线程 |
| 18 | |
| 19 | if ((maxThreads > 0) && (curThreads < maxThreads)) { |
| 20 | |
| 21 | curThreadsBusy++; |
| 22 | |
| 23 | return (newWorkerThread()); |
| 24 | |
| 25 | } else { |
| 26 | |
| 27 | //如果maxThreads小于0，则说明没有限制，创建新的线程 |
| 28 | |
| 29 | if (maxThreads < 0) { |
| 30 | |
| 31 | curThreadsBusy++; |
| 32 | |
| 33 | return (newWorkerThread()); |
| 34 | |
| 35 | } else { |
| 36 | |
| 37 | return (null); |
| 38 | |
| 39 | } |
| 40 | |
| 41 | } |
| 42 | |
| 43 | } |
| 44 | |
| 45 | } |
| 46 | |
| 47 |
工作线程回收
JIoEndPoint中recycleWorkerThread方法是回收工作线程，当http请求处理完成，则调用该方法回收工作线程。该方法首先获得worker对象锁，然后调用workers.push方法将工作线程压入工作线程栈中，接着将当前繁忙线程数减1，最后调用workers.notify方法。
| 1 | protected void recycleWorkerThread(Worker workerThread) { |
| 2 | |
| 3 | synchronized (workers ) { |
| 4 | |
| 5 | workers.push(workerThread); |
| 6 | |
| 7 | curThreadsBusy--; |
| 8 | |
| 9 | workers.notify(); |
| 10 | |
| 11 | } |
| 12 | } |
配置
在Tomcat中配置文件Server.xml中的Connector属性配置最大线程数maxThreads。
例如：
<Connector port="8080"
maxThreads="150"
……/>
Acceptor线程
功能
获得HTTP请求socket。并从工作线程池中获得一个线程，将socket分配给一个工作线程。
名称
http-[IPAddr]-[Port]-Acceptor-[Number]，如http-0.0.0.0-8080-Acceptor-1
线程类：JIoEndpoint.Acceptor
所属线程池
无
启动时序图
在启动时会开启Accepter线程，时序图如下：
线程启动
如上时序图，在Tomcat启动过程会调用JIoEndpoint类的start方法，会创建并启动acceptorThreadCount个Acceptor线程。
| 1 | public void start() throws Exception { |
| 2 | |
| 3 | // Initialize socket if not done before |
| 4 | |
| 5 | if (!initialized ) { |
| 6 | |
| 7 | init(); |
| 8 | |
| 9 | } |
| 10 | |
| 11 | if (!running ) { |
| 12 | |
| 13 | running = true ; |
| 14 | |
| 15 | paused = false ; |
| 16 | |
| 17 | //如果没有配置executor线程池，则创建工作线程栈worker, 就是上例中的线程池的工作线程栈。 |
| 18 | |
| 19 | if (executor == null) { |
| 20 | |
| 21 | workers = new WorkerStack(maxThreads); |
| 22 | |
| 23 | } |
| 24 | |
| 25 | //启动acceptor线程 |
| 26 | |
| 27 | for (int i = 0; i < acceptorThreadCount; i++) { |
| 28 | |
| 29 | Thread acceptorThread = new Thread(new Acceptor(), getName() + "-Acceptor-" + i); |
| 30 | |
| 31 | acceptorThread.setPriority( threadPriority); |
| 32 | |
| 33 | acceptorThread.setDaemon( daemon); |
| 34 | |
| 35 | acceptorThread.start(); |
| 36 | |
| 37 | } |
| 38 | |
| 39 | } |
| 40 | |
| 41 | } |
属性
acceptorThreadCount:开启的acceptor线程数，从源码看到这个值并没有通过配置设置，而是固定的值为1
配置
无
Main主线程
功能
完成装配、初始化和启动，之后会开启SocketServer，并循环等待命令，如shutdown。
名称：Main
线程类：Main主线程
所属线程池：
无
catalina-exec线程
功能
StandardThreadExecutor的工作线程，功能和Work线程类似。如果为Connector配置了Executor，则会使用该线程处理http请求。
线程类：ThreadPoolExecutor.Work
所属线程池:StandardThreadExecutor
类名是org.apache.catalina.core.StandardThreadExecutor，该线程池类通过代理设计模式对Java Concurrent包中的线程池ThreadPoolExecutor进行简单的封装。并实现了Lifecycle接口，以及增加了发送消息的功能。
属性
minSpareThreads：最小空闲线程数
maxThreads:最大线程数
maxIdleTime：最大空闲时间
配置
在Server.xml文件中配置Executor节点，支持如下属性，
|
Name |
Executor的名称 |
|
namePrefix |
工作线程前缀 |
|
maxThreads |
最大线程数 |
|
minSpareThreads |
最小空闲线程数 |
|
maxIdleTime |
最大空闲时间 |
并在Connector节点配置executor，并指定为Executor的名称。
例如：
<Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="150" minSpareThreads="4" maxIdleTime="200"/>
<Connector Address="0.0.0.0" port="8080" protocol="HTTP/1.1"executor="tomcatThreadPool".../>
TP-Processor线程
功能
AJP协议中Servlet容器的处理线程
名称
TP-Processor-[Number],例如TP-Processor-1
线程类：ThreadPool.ControlRunnable
所属线程池：org.apache.tomcat.util.threads.ThreadPool
该线程池还会启动一个TP-Monitor线程监控空闲线程。在TheadPool会有一个ControlRunnable数组保存线程池中的工作线程。使用该线程池需要先调用start方法，进行ControlRunnable数组初始化，minSpareThreads个空闲线程的创建，以及TP-Monitor线程的启动。
属性
maxThreads：最大线程数
minSpareThreads：最小空闲线程数
maxSpareThreads: 最大空闲线程数
线程池的启动
通过ThreadPool.start方法，该方法会分配线程数组pool，并打开minSpareThreads空线程。如果最大空闲线程数小于最大线程数，则启动TP-Monitor线程。
| 1 | public synchronized void start() { |
| 2 | |
| 3 | stopThePool=false ; |
| 4 | |
| 5 | currentThreadCount = 0; |
| 6 | |
| 7 | currentThreadsBusy = 0; |
| 8 | |
| 9 | adjustLimits(); |
| 10 | |
| 11 | pool = new ControlRunnable[maxThreads]; |
| 12 | |
| 13 | //启动minSpareThreads空闲线程 |
| 14 | |
| 15 | openThreads( minSpareThreads); |
| 16 | |
| 17 | //如果最大空闲线程数小于最大线程数，则启动TP-Monitor线程 |
| 18 | |
| 19 | if (maxSpareThreads < maxThreads) { |
| 20 | |
| 21 | monitor = new MonitorRunnable(this); |
| 22 | |
| 23 | } |
| 24 | |
| 25 | } |
任务分配
使用ThreadPool.runIt来运行新的任务，在该方法中，会调用findControlRunnable方法来获得一个工作线程。需要注意的是调用方不需要调用额外的方法来回收线程。当ControlRunnable线程完成指定的任务会自动将线程回收到线程池中。
findControlRunnable是ThreadPool线程池的关键方法，它提供了从线程池中获得一个工作线程，并将相应的计数调整，如 tpOpen，currentThreadsBusy。
| 1 | /** |
| 2 | |
| 3 | * Executes a given Runnable on a thread in the pool, block if needed. |
| 4 | |
| 5 | */ |
| 6 | |
| 7 | public void runIt(ThreadPoolRunnable r) { |
| 8 | |
| 9 | if(null == r) { |
| 10 | |
| 11 | throw new NullPointerException(); |
| 12 | |
| 13 | } |
| 14 | |
| 15 | //从线程池中获得一个工作线程 |
| 16 | |
| 17 | ControlRunnable c = findControlRunnable(); |
| 18 | |
| 19 | //运行任务 |
| 20 | |
| 21 | c.runIt(r); |
| 22 | |
| 23 | } |
| 24 | |
| 25 | private ControlRunnable findControlRunnable() { |
| 26 | |
| 27 | ControlRunnable c= null; |
| 28 | |
| 29 | if ( stopThePool ) { |
| 30 | |
| 31 | throw new IllegalStateException(); |
| 32 | |
| 33 | } |
| 34 | |
| 35 | //从线程池中获得一个空闲线程 |
| 36 | |
| 37 | synchronized(this ) { |
| 38 | |
| 39 | //当前繁忙线程和当前线程数相同，则表示所有的开启线程都是繁忙的。 |
| 40 | |
| 41 | while (currentThreadsBusy == currentThreadCount) { |
| 42 | |
| 43 | //如果当前线程数比最大线程数小 |
| 44 | |
| 45 | if (currentThreadCount < maxThreads) { |
| 46 | |
| 47 | // Not all threads were open, |
| 48 | |
| 49 | // Open new threads up to the max number of idel threads |
| 50 | |
| 51 | |
| 52 | int toOpen = currentThreadCount + minSpareThreads; |
| 53 | |
| 54 | openThreads(toOpen); |
| 55 | |
| 56 | } else { |
| 57 | |
| 58 | logFull(log, currentThreadCount, maxThreads ); |
| 59 | |
| 60 | //线程数已经满了，等待线程成为空闲线程 |
| 61 | |
| 62 | try { |
| 63 | |
| 64 | this.wait(); |
| 65 | |
| 66 | } |
| 67 | |
| 68 | // was just catch Throwable -- but no other |
| 69 | |
| 70 | // exceptions can be thrown by wait, right? |
| 71 | |
| 72 | // So we catch and ignore this one, since |
| 73 | |
| 74 | // it\'ll never actually happen, since nowhere |
| 75 | |
| 76 | // do we say pool.interrupt(). |
| 77 | |
| 78 | catch(InterruptedException e) { |
| 79 | |
| 80 | log.error("Unexpected exception" , e); |
| 81 | |
| 82 | } |
| 83 | |
| 84 | if( log .isDebugEnabled() ) { |
| 85 | |
| 86 | log.debug("Finished w 以上是关于tomcat线程初探的主要内容，如果未能解决你的问题，请参考以下文章 |