1. 获得客户端的socket
2. 将获得的socket交给该类线程池(是由一个栈实现的)中的闲置线程
3. 各线程调用AprEndpoint中的handler变量对socket进行处理(process()函数)
注:handler是AjpConnectionHandler或者Http11ConnectionHandler的实例。
看这个之前,我是有几个问题不太确定,所以看了一下源代码,什么问题呢?
tomcat的socket是非阻塞式工作吗?
多线程处理请求到底是在哪个环节开始的呢?
看了之后,发现,tomcat的socket居然是阻塞式的
long socket = Socket.accept(serverSock); // 从线程池中取出闲置线程来处理收到的socket getWorkerThread().assign(socket, true);
该线程类叫Worker,用了assign和await两个函数来实现生产者和消费者模型,个人觉得有点多余。通过getWorkerThread()拿到的一定是闲置线程,还搞什么同步呢?
protected class Worker implements Runnable { protected Thread thread = null; protected boolean available = false; protected long socket = 0; protected boolean options = false; protected synchronized void assign(long socket, boolean options) { // Wait for the Processor to get the previous Socket while (available) { try { wait(); } catch (InterruptedException e) { } } // Store the newly available Socket and notify our thread this.socket = socket; this.options = options; available = true; notifyAll(); } /** * Await a newly assigned Socket from our Connector, or <code>null</code> * if we are supposed to shut down. */ protected synchronized long await() { // Wait for the Connector to provide a new Socket while (!available) { try { wait(); } catch (InterruptedException e) { } } // Notify the Connector that we have received this Socket long socket = this.socket; available = false; notifyAll(); return (socket); } /** * The background thread that listens for incoming TCP/IP connections and * hands them off to an appropriate processor. */ public void run() { // Process requests until we receive a shutdown signal while (running) { // Wait for the next socket to be assigned long socket = await(); if (socket == 0) continue; // Process the request from this socket if ((options && !setSocketOptions(socket)) || !handler.process(socket)) { // Close socket and pool Socket.destroy(socket); socket = 0; } // Finish up this request recycleWorkerThread(this); } } /** * Start the background processing thread. */ public void start() { thread = new ThreadWithAttributes(AprEndpoint.this, this); thread.setName(getName() + "-" + (++curThreads)); thread.setDaemon(true); thread.start(); } }