1.源码包结构
2.测试线程
1.启动mina-example下echoserver#Main
2.启动jconsole查看线程:
1.NioSocketAcceptor
Runnable 为 AbstractPollingIoAcceptor$Acceptor
3. 启动 com.game.landon.entrance. EchoClient, 连接已启动的 echoserver.
->此时查看线程->多了一个
2.NioProcessor
Runnable为AbstractPollingIoProcessor$Processor
4.两个线程池来源:
1.AbstractIoService(IoSessionConfig sessionConfig,Executor executor)
该构造函数中判断
if(executor == null){
this.executor = Executors.newCachedThreadPool();
}
详见源码.
2.SimpleIoProcessorPool
其构造函数判断同上
3.内部基本流程
1.SocketAcceptor acceptor = new NioSocketAcceptor();
1.初始化NioSocketAcceptor线程池 {@link AbstractIoService }
2.初始化NioProcessor线程池 {@link SimpleIoProcessorPool }
3. NioSocketAcceptor#init
初始化Selector:selector = Selector.open();
2.acceptor.bind(new InetSocketAddress(PORT));
1.AbstractPollingIoAcceptor#bindInternal
#startupAcceptor
- >NioSocketAcceptor线程池执行Acceptor这个任务.
3.Acceptor#run
1.while(selectable)
1.selector.select
2.#registerHandles
->NioSocketAcceptor#open
设置socket选项并向selector注册OP_ACCEPT事件
3.#processHandles
1.NioSocketAcceptor#accept->返回NioSocketSession
2.SimpleIoProcessorPool#add
1.根据sessionId将session与pool中的某个NioProcessor绑定 {@link SimpleIoProcessorPool#getProcessor}
2.AbstractPollingIoProcessor#add
3. AbstractPollingIoProcessor#startupProcessor
->NioProcessor线程池执行Processor这个任务
//
从这段代码看出:
//
1.Processor这个任务只会创建一次.即每一个NioProcessor对象最多拥有一个Processor
//
2.每个NioProcessor只会向线程池提交一次Processor任务.而Processor任务是一个无限循环的任务.
//
也可以说,每个Processor就占据着线程池的一个线程.->即每个NioProcessor对象对应线程池中的一个线程
//
3.而session是与某个固定的NioProcessor绑定的(取模)->也就是说每个session的处理都是单线程的.(均在NioProcessor的唯一Processor线程执行)
//
4.public NioSocketAcceptor(int processorCount)构造中可指定processor的数目,其实最终是指定CacheThreadPool中多少用于prossor的线程数目.//(默认:private static final int DEFAULT_SIZE = Runtime.getRuntime().availableProcessors() + 1)
// 5.每个NioProcessor中只有一个selector.
private
void
startupProcessor()
{
Processor processor = processorRef.get();
if (processor == null) { processor = new Processor(); if (processorRef.compareAndSet(null, processor)) { executor.execute(new NamePreservingRunnable(processor, threadName));
} } // Just stop the select() and start it again, so that the processor // can be activated immediately. wakeup();
}
{{{{{{{{{{{{{{{{{
2.Processor#run
1.for(;;)
1.select(SELECT_TIMEOUT)
2.#handleNewSessions
1. AbstractPollingIoProcessor#addNow
2. AbstractPollingIoProcessor#init
NioProcessor#init->session.getChannel向selector注册OP_READ事件
3.#updateTrafficmask
4.#process
//process reads/process writes
5.#flush
6.#nofifyIdleSessions
/** */
/** * The main loop. This is the place in charge to poll the Selector, and to * process the active sessions. It's done in * - handle the newly created sessions * - */
private
class
Processor
implements
Runnable
{ public void run() { assert (processorRef.get() == this); int nSessions = 0; lastIdleCheckTime = System.currentTimeMillis(); for (;;) { try { // This select has a timeout so that we can manage // idle session when we get out of the select every // second. (note : this is a hack to avoid creating // a dedicated thread). long t0 = System.currentTimeMillis(); int selected = select(SELECT_TIMEOUT); long t1 = System.currentTimeMillis(); long delta = (t1 - t0); if ((selected == 0) && !wakeupCalled.get() && (delta < 100)) { // Last chance : the select() may have been // interrupted because we have had an closed channel. if (isBrokenConnection()) { LOG.warn("Broken connection"); // we can reselect immediately // set back the flag to false wakeupCalled.getAndSet(false); continue; } else { LOG.warn("Create a new selector. Selected is 0, delta = " + (t1 - t0)); // Ok, we are hit by the nasty epoll // spinning. // Basically, there is a race condition // which causes a closing file descriptor not to be // considered as available as a selected channel, but // it stopped the select. The next time we will // call select(), it will exit immediately for the same // reason, and do so forever, consuming 100% // CPU. // We have to destroy the selector, and // register all the socket on a new one. registerNewSelector(); } // Set back the flag to false wakeupCalled.getAndSet(false); // and continue the loop continue; } // Manage newly created session first nSessions += handleNewSessions(); updateTrafficMask(); // Now, if we have had some incoming or outgoing events, // deal with them if (selected > 0) { //LOG.debug("Processing "); // This log hurts one of the MDCFilter test process(); } // Write the pending requests long currentTime = System.currentTimeMillis(); flush(currentTime); // And manage removed sessions nSessions -= removeSessions(); // Last, not least, send Idle events to the idle sessions notifyIdleSessions(currentTime); // Get a chance to exit the infinite loop if there are no // more sessions on this Processor if (nSessions == 0) { processorRef.set(null); if (newSessions.isEmpty() && isSelectorEmpty()) { // newSessions.add() precedes startupProcessor assert (processorRef.get() != this); break; } assert (processorRef.get() != this); if (!processorRef.compareAndSet(null, this)) { // startupProcessor won race, so must exit processor assert (processorRef.get() != this); break; } assert (processorRef.get() == this); } // Disconnect all sessions immediately if disposal has been // requested so that we exit this loop eventually. if (isDisposing()) { for (Iterator<S> i = allSessions(); i.hasNext();) { scheduleRemove(i.next()); } wakeup(); } } catch (ClosedSelectorException cse) { // If the selector has been closed, we can exit the loop break; } catch (Throwable t) { ExceptionMonitor.getInstance().exceptionCaught(t); try { Thread.sleep(1000); } catch (InterruptedException e1) { ExceptionMonitor.getInstance().exceptionCaught(e1); } } } try { synchronized (disposalLock) { if (disposing) { doDispose(); } } } catch (Throwable t) { ExceptionMonitor.getInstance().exceptionCaught(t); } finally { disposalFuture.setValue(true); } } }
4.相关类图关系
1.IoService关系类图
2.IoProcessor关系类图
3.IoSession关系类图
5.总结:
本篇只是引入篇，着重介绍了mina2内部的两个acceptor线程池和processor线程池.关于nio相关请看我之前的文章.