可以看到最终是调用了父类MultithreadEventExecutorGroup的构造方法，继续跟踪：
查看代码protected MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory, Object... args) { this(nThreads, threadFactory == null ? null : new ThreadPerTaskExecutor(threadFactory), args); } protected MultithreadEventExecutorGroup(int nThreads, Executor executor, Object... args) { this(nThreads, executor, DefaultEventExecutorChooserFactory.INSTANCE, args); } protected MultithreadEventExecutorGroup(int nThreads, Executor executor, EventExecutorChooserFactory chooserFactory, Object... args) { checkPositive(nThreads, "nThreads"); if (executor == null) { //创建线程执行器以及线程工厂 executor = new ThreadPerTaskExecutor(newDefaultThreadFactory()); } //根据线程数构建EventExecutor数组 children = new EventExecutor[nThreads]; for (int i = 0; i < nThreads; i ++) { boolean success = false; try { //初始化数组中的线程，由NioEventLoopGroup创建NioEventLoop实例 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 { //当初始化失败时，需要优雅关闭，清理资源 if (!success) { for (int j = 0; j < i; j ++) { children[j].shutdownGracefully(); } for (int j = 0; j < i; j ++) { EventExecutor e = children[j]; try { //当线程未终止时，等待终止 while (!e.isTerminated()) { e.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS); } } catch (InterruptedException interrupted) { // Let the caller handle the interruption. Thread.currentThread().interrupt(); break; } } } } } //根据线程数创建选择器，选择器主要适用于next()方法 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); } } }; //为每个EventLoop线程增加线程终止监听器 for (EventExecutor e: children) { e.terminationFuture().addListener(terminationListener); } Set<EventExecutor> childrenSet = new LinkedHashSet<EventExecutor>(children.length); Collections.addAll(childrenSet, children); //创建执行器数组只读副本，便于在迭代查询时使用 readonlyChildren = Collections.unmodifiableSet(childrenSet); }