做网站排名公司推荐,做问卷的网站哪个好,php做简易网站,新浪网页版电脑版NioEventLoopGroup 可以看到NioEventLoopGroup继承了MultithreadEventExecutorGroup并且实现了EventLoopGroup接口#xff0c;而这两个类被ExecutorService修饰#xff0c;所以NioEventLoopGroup实际上是一个线程池#xff0c;池中的对象其实就是单个的NioEventLoop。
源码…NioEventLoopGroup 可以看到NioEventLoopGroup继承了MultithreadEventExecutorGroup并且实现了EventLoopGroup接口而这两个类被ExecutorService修饰所以NioEventLoopGroup实际上是一个线程池池中的对象其实就是单个的NioEventLoop。
源码解读
NioEventLoopGroup 的参数初始化 // 进入无参构造public NioEventLoopGroup() {this(0);} public NioEventLoopGroup(int nThreads) {// group所包含的executorthis(nThreads, (Executor) null);}public NioEventLoopGroup(int nThreads, Executor executor) {// 注入单例模式的提供者 this(nThreads, executor, SelectorProvider.provider());}public NioEventLoopGroup(int nThreads, Executor executor, final SelectorProvider selectorProvider) {// 注入默认的策略工厂实例this(nThreads, executor, selectorProvider, DefaultSelectStrategyFactory.INSTANCE);}public NioEventLoopGroup(int nThreads, Executor executor, final SelectorProvider selectorProvider,final SelectStrategyFactory selectStrategyFactory) { // 注入拒绝处理器super(nThreads, executor, selectorProvider, selectStrategyFactory, RejectedExecutionHandlers.reject());}protected MultithreadEventLoopGroup(int nThreads, Executor executor, Object... args) {super(nThreads 0 ? DEFAULT_EVENT_LOOP_THREADS : nThreads, executor, args);}private static final int DEFAULT_EVENT_LOOP_THREADS;static {//默认线程数是cpu核数的两倍DEFAULT_EVENT_LOOP_THREADS Math.max(1, SystemPropertyUtil.getInt(io.netty.eventLoopThreads, NettyRuntime.availableProcessors() * 2));if (logger.isDebugEnabled()) {logger.debug(-Dio.netty.eventLoopThreads: {}, DEFAULT_EVENT_LOOP_THREADS);}}构造真正的NioEventGroup
protected MultithreadEventExecutorGroup(int nThreads, Executor executor,EventExecutorChooserFactory chooserFactory, Object... args) {if (nThreads 0) {throw new IllegalArgumentException(String.format(nThreads: %d (expected: 0), nThreads));}//1、//executor校验非空, 如果为空就创建ThreadPerTaskExecutor, 该类实现了 Executor接// 这个executor 是用来执行线程池中的所有的线程也就是所有的NioEventLoop其实从//NioEventLoop构造器中也可以知道NioEventLoop构造器中都传入了executor这个参数。if (executor null) {executor new ThreadPerTaskExecutor(newDefaultThreadFactory());}//2、//这里的children数组 其实就是线程池的核心实现线程池中就是通过指定的线程数组来实现 线程池//数组中每个元素其实就是一个EventLoopEventLoop是EventExecutor的子接口。children new EventExecutor[nThreads];for (int i 0; i nThreads; i ) {boolean success false;try {//3、//newChild(executor, args) 函数在NioEventLoopGroup类中实现了,// 实质就是就是存入了一个 NIOEventLoop类实例children[i] newChild(executor, args);success true;} catch (Exception e) {// TODO: Think about if this is a good exception typethrow new IllegalStateException(failed to create a child event loop, e);} finally {if (!success) {for (int j 0; j i; j ) {children[j].shutdownGracefully();}// 终止所有eventLoop上所执行的任务for (int j 0; j i; j ) {EventExecutor e children[j];try {while (!e.isTerminated()) {e.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS);}} catch (InterruptedException interrupted) {// Let the caller handle the interruption.Thread.currentThread().interrupt();break;}}}}}
//4、实例化线程工厂执行器选择器: 根据children获取选择器chooser chooserFactory.newChooser(children);//5、为每个EventLoop线程添加 线程终止监听器final FutureListenerObject terminationListener new FutureListenerObject() {Overridepublic void operationComplete(FutureObject future) throws Exception {if (terminatedChildren.incrementAndGet() children.length) {terminationFuture.setSuccess(null);}}};for (EventExecutor e: children) {e.terminationFuture().addListener(terminationListener);}
//6、将children 添加到对应的set集合中去重 表示只可读。SetEventExecutor childrenSet new LinkedHashSetEventExecutor(children.length);Collections.addAll(childrenSet, children);readonlyChildren Collections.unmodifiableSet(childrenSet);}children[i] newChild(executor, args);
/*** newChild(executor, args) 里的方法* 我们可以看到 返回的就是一个 NioEventLoop*/
Override
protected EventLoop newChild(Executor executor, Object... args) throws Exception {return new NioEventLoop(this, executor, (SelectorProvider) args[0],((SelectStrategyFactory) args[1]).newSelectStrategy(), (RejectedExecutionHandler) args[2]);
}1. NioEventLoopGroup初始化时未指定线程数那么会使用默认线程数即 线程数 CPU核心数 * 2
2. 每个NioEventLoopGroup对象内部都有一组可执行的NioEventLoop数组其大小是 nThreads, 这样就构成了一个线程池 一个NIOEventLoop可以理解成就是一个线程。
3. 所有的NIOEventLoop线程是使用相同的 executor、SelectorProvider、SelectStrategyFactory、RejectedExecutionHandler以及是属于某一个NIOEventLoopGroup的。这一点从 newChild(executor, args); 方法就可以看出newChild()的实现是在NIOEventLoopGroup中实现的。
4. 当有IO事件来时需要从线程池中选择一个线程出来执行这时候的NioEventLoop选择策略是由GenericEventExecutorChooser实现的并调用该类的next()方法。
5. 每个NioEventLoopGroup对象都有一个NioEventLoop选择器与之对应其会根据NioEventLoop的个数动态选择chooser如果是2的幂次方则按位运算否则使用普通的轮询
