NettyPoolCloseTest.java

import io.netty.bootstrap.Bootstrap;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.util.concurrent.Future;
import org.junit.After;
import org.junit.Test;

import java.net.SocketAddress;

import static java.util.concurrent.TimeUnit.*;

public class NettyPoolCloseTest {
    
    private final EventLoopGroup serverGroup = new NioEventLoopGroup();
    private final EventLoopGroup clientGroup = new NioEventLoopGroup(1);

    @After
    public void tearDown() {
        serverGroup.shutdownGracefully();
        clientGroup.shutdownGracefully();
    }

    @Test
    public void poolClose() throws Exception {
        ServerBootstrap serverBootstrap = createServerBootstrap();
        Channel serverChannel = serverBootstrap.bind(0).sync().channel();
        SocketAddress serverAddress = serverChannel.localAddress();

        Bootstrap clientBootstrap = createClientBootstrap(serverAddress);
        FixedChannelPool pool = new FixedChannelPool(clientBootstrap, new EmptyChannelPoolHandler(), 5);

        Channel clientChannel = pool.acquire().get(60, SECONDS);
        ByteBuf msg = clientChannel.alloc().ioBuffer(4).writeInt(42);
        clientChannel.writeAndFlush(msg);
        pool.release(clientChannel).get(60, SECONDS);

        pool.close();
        clientGroup.shutdownGracefully();
        clientGroup.terminationFuture().awaitUninterruptibly(); // this line is expected to hang
    }

    private ServerBootstrap createServerBootstrap() {
        return new ServerBootstrap()
                .group(serverGroup)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) {
                        ch.pipeline().addFirst(new LoggingHandler(LogLevel.DEBUG));
                        ch.pipeline().addLast(new ServerHandler());
                    }
                });
    }

    private Bootstrap createClientBootstrap(SocketAddress serverAddress) {
        return new Bootstrap()
                .group(clientGroup)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) {
                        ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                    }
                })
                .remoteAddress(serverAddress);
    }

    private static class ServerHandler extends SimpleChannelInboundHandler<ByteBuf> {
        @Override
        protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) {
            msg.readerIndex(msg.readableBytes());
        }
    }

    private static class EmptyChannelPoolHandler implements ChannelPoolHandler {
        @Override
        public void channelReleased(Channel ch) {
        }

        @Override
        public void channelAcquired(Channel ch) {
        }

        @Override
        public void channelCreated(Channel ch) {
        }
    }
}