Question

I`m trying to test netty, but when i creating a multiple clients to connect to server, some of client just froze and never finish.
Here my code( basically i used code from her https://github.com/brunodecarvalho/netty-tutorials and just modify it to use a several clients):

 for (int i = numthr; i > 0; i--) {
            Runnable runner = new Runnable() {
                public void run() {
                    final Client client = new Client("localhost", 10400, nummes, 0);
                    if (!client.start()) {
                        System.exit(-1);
                        return;
                    }
                    client.flood();
                    Runtime.getRuntime().addShutdownHook(new Thread() {
                        @Override
                        public void run() {
                            client.stop();
                        }
                    });
                }
            };
            executor.execute(runner);
        }

    public void messageReceived(Envelope message) {

        if (this.received.incrementAndGet() == this.messages) {

            System.out.println(nmb.incrementAndGet());


        }
    }

     public boolean start() {

        // For production scenarios, use limited sized thread pools
        this.clientFactory = new NioClientSocketChannelFactory(Executors.newCachedThreadPool(),
                                                               Executors.newCachedThreadPool(),1);
        this.channelGroup = new DefaultChannelGroup(this + "-channelGroup");
        this.handler = new ClientHandler(this, this.channelGroup);
        ChannelPipelineFactory pipelineFactory = new ChannelPipelineFactory() {

            @Override
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline pipeline = Channels.pipeline();
                pipeline.addLast("encoder", new Encoder());
                pipeline.addLast("decoder", new Decoder());
                pipeline.addLast("handler", handler);
                return pipeline;
            }
        };

        ClientBootstrap bootstrap = new ClientBootstrap(this.clientFactory);
        bootstrap.setOption("reuseAddress", true);
        bootstrap.setOption("tcpNoDelay", true);
        bootstrap.setOption("keepAlive", true);
        bootstrap.setPipelineFactory(pipelineFactory);


        boolean connected = bootstrap.connect(new InetSocketAddress(host, port)).awaitUninterruptibly().isSuccess();
        if (!connected) {
            this.stop();
        }

        return connected;
    }

       this.serverFactory = new NioServerSocketChannelFactory(Executors.newCachedThreadPool(),
                                                               Executors.newCachedThreadPool());
        this.channelGroup = new DefaultChannelGroup(this + "-channelGroup");
        ExecutionHandler executionHandler = new ExecutionHandler(
                new MemoryAwareThreadPoolExecutor(270, 1048576, 1048576));

        ServerBootstrap bootstrap = new ServerBootstrap(this.serverFactory);
        bootstrap.setPipelineFactory(
                new DatabaseGatewayPipelineFactory(executionHandler));
        bootstrap.setOption("reuseAddress", true);
        bootstrap.setOption("child.tcpNoDelay", true);
        bootstrap.setOption("child.keepAlive", true);
        bootstrap.setOption("child.connectTimeoutMillis", 10000);

        Channel channel = bootstrap.bind(new InetSocketAddress(this.host, this.port));
        if (!channel.isBound()) {
            this.stop();
            return false;
        }

        this.channelGroup.add(channel);

Answer 1

The code is making new thread for Client each time, with same port number. This can create problems, because multiple threads are processing messages on the same port.