public void rebuildSelector() {
        if (!inEventLoop()) {
            execute(new Runnable() {
                @Override
                public void run() {
                    rebuildSelector0();
                }
            });
            return;
        }
        rebuildSelector0();
    }
@Test
    public void testRebuildSelector() {
        EventLoopGroup group = new NioEventLoopGroup(1);
        final NioEventLoop loop = (NioEventLoop) group.next();
        try {
            Channel channel = new NioServerSocketChannel();
            loop.register(channel).syncUninterruptibly();

            Selector selector = loop.unwrappedSelector();
            assertSame(selector, ((NioEventLoop) channel.eventLoop()).unwrappedSelector());
            assertTrue(selector.isOpen());

            // Submit to the EventLoop so we are sure its really executed in a non-async manner.
            loop.submit(new Runnable() {
                @Override
                public void run() {
                    loop.rebuildSelector();
                }
            }).syncUninterruptibly();

            Selector newSelector = ((NioEventLoop) channel.eventLoop()).unwrappedSelector();
            assertTrue(newSelector.isOpen());
            assertNotSame(selector, newSelector);
            assertFalse(selector.isOpen());

            channel.close().syncUninterruptibly();
        } finally {
            group.shutdownGracefully();
        }
    }