目录

类结构图1.1 构造方法1.1.1 newChild

类结构图

1.1 构造方法

public NioEventLoopGroup() { this(0); } public NioEventLoopGroup(int nThreads) { this(nThreads, (Executor) null); } public NioEventLoopGroup(int nThreads, Executor executor) { this(nThreads, executor, SelectorProvider.provider()); } public NioEventLoopGroup( int nThreads, Executor executor, final SelectorProvider selectorProvider) { this(nThreads, executor, selectorProvider, DefaultSelectStrategyFactory.INSTANCE); } public NioEventLoopGroup(int nThreads, Executor executor, final SelectorProvider selectorProvider, final SelectStrategyFactory selectStrategyFactory) { super(nThreads, executor, selectorProvider, selectStrategyFactory, RejectedExecutionHandlers.reject()); }

类 MultithreadEventLoopGroup

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 { 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); } }

可以看到如果调用无参构造，线程数会是 2*Ncpu，这适合 workerEventLoopGroup。 创建 bossEventLoopGroup 就需要加个参数 1。

类 MultithreadEventExecutorGroup

protected MultithreadEventExecutorGroup(int nThreads, Executor executor, Object... args) { this(nThreads, executor, DefaultEventExecutorChooserFactory.INSTANCE, args); } protected MultithreadEventExecutorGroup(int nThreads, Executor executor, EventExecutorChooserFactory chooserFactory, Object... args) { if (nThreads <= 0) { throw new IllegalArgumentException(String.format("nThreads: %d (expected: > 0)", nThreads)); } if (executor == null) { //实例化每个EventLoop所需要的执行器Executor 见（2） executor = new ThreadPerTaskExecutor(newDefaultThreadFactory()); } //NioEventLoop是EventExecutor的实现类 children = new EventExecutor[nThreads]; for (int i = 0; i < nThreads; i ++) { boolean success = false; try { //见1.1.1 children[i] = newChild(executor, args); success = true; } catch (Exception e) { // TODO: Think about if this is a good exception type throw new IllegalStateException("failed to create a child event loop", e); } finally { if (!success) { for (int j = 0; j < i; j ++) { children[j].shutdownGracefully(); } 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; } } } } } chooser = chooserFactory.newChooser(children); final FutureListener<Object> terminationListener = new FutureListener<Object>() { @Override public void operationComplete(Future<Object> future) throws Exception { if (terminatedChildren.incrementAndGet() == children.length) { terminationFuture.setSuccess(null); } } }; for (EventExecutor e: children) { e.terminationFuture().addListener(terminationListener); } Set<EventExecutor> childrenSet = new LinkedHashSet<EventExecutor>(children.length); Collections.addAll(childrenSet, children); readonlyChildren = Collections.unmodifiableSet(childrenSet); }

1.1.1 newChild

类 MultithreadEventExecutorGroup

protected abstract EventExecutor newChild(Executor executor, Object... args) throws Exception;

这是一个接口

类 NioEventLoopGroup

@Override protected EventLoop newChild(Executor executor, Object... args) throws Exception { //见（3） return new NioEventLoop(this, executor, (SelectorProvider) args[0], ((SelectStrategyFactory) args[1]).newSelectStrategy(), (RejectedExecutionHandler) args[2]); }