MultithreadEventExecutorGroup是核心，管理eventLoop的生命周期，先看看其中几个变量。
1、children：EventExecutor数组，保存eventLoop。
2、chooser：从children中选取一个eventLoop的策略。
构造方法：
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protected MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory, Object... args) { if (nThreads <= 0) { throw new IllegalArgumentException(String.format("nThreads: %d (expected: > 0)", nThreads)); } if (threadFactory == null) { threadFactory = newDefaultThreadFactory(); } children = new SingleThreadEventExecutor[nThreads]; if (isPowerOfTwo(children.length)) { chooser = new PowerOfTwoEventExecutorChooser(); } else { chooser = new GenericEventExecutorChooser(); } for (int i = 0; i < nThreads; i ++) { boolean success = false; try { children = newChild(threadFactory, 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) { Thread.currentThread().interrupt(); break; } } } } } 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); }} protected EventExecutor newChild( ThreadFactory threadFactory, Object... args) throws Exception { return new NioEventLoop(this, threadFactory, (SelectorProvider) args[0]); }[url=][/url]
1、 根据数组的大小，采用不同策略初始化chooser。
如果大小为2的幂次方，则采用PowerOfTwoEventExecutorChooser；否则使用GenericEventExecutorChooser。
判断一个数是否是2的幂次方的方法，觉得很赞。
private static boolean isPowerOfTwo(int val) { return (val & -val) == val;}2、newChild方法重载，初始化EventExecutor时，实际执行的是NioEventLoopGroup中的newChild方法，所以，children元素的实际类型为NioEventLoop。
接下去看看NioEventLoop类。 |
