java - netty4测试过程中出现"java.lang.NullPointerException"

Question

我只是想测试一下netty4支持的TCP持久连接数量，当数量达到1337时，客户端出现如下新信息

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java.lang.NullPointerException at sun.nio.ch.EPollArrayWrapper.setUpdateEvents(EPollArrayWrapper.java:178) at sun.nio.ch.EPollArrayWrapper.add(EPollArrayWrapper.java:227) at sun.nio.ch.EPollSelectorImpl.implRegister(EPollSelectorImpl.java:164) at sun.nio.ch.SelectorImpl.register(SelectorImpl.java:133) at java.nio.channels.spi.AbstractSelectableChannel.register(AbstractSelectableChannel.java:209) at io.netty.channel.nio.AbstractNioChannel.doRegister(AbstractNioChannel.java:285) at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:438) at io.netty.channel.AbstractChannel$AbstractUnsafe.access$100(AbstractChannel.java:373) at io.netty.channel.AbstractChannel$AbstractUnsafe$1.run(AbstractChannel.java:417) at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:354) at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:348) at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:101) at java.lang.Thread.run(Thread.java:724)

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客户端代码是:

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public class HSFTCPClient {

     private final String host;
     private final int port;


     public HSFTCPClient(String host,int port){
         this.host = host;
         this.port = port;
     }

     public void run() throws Exception {
            EventLoopGroup workerGroup = new NioEventLoopGroup();
            try {
                Bootstrap b = new Bootstrap();
                 b.group(workerGroup);
                 b.channel(NioSocketChannel.class);

                  //Note that we do not use childOption() here unlike we did with
                 // ServerBootstrap because the client-side SocketChannel does not have a parent.
                 b.option(ChannelOption.SO_KEEPALIVE, true);

                 b.handler(new HSFClientInitializer());

                // Make a new connection.
                 ChannelFuture f = b.connect(host, port).sync();
                 Channel ch = f.channel();

            } finally {
                     //workerGroup.shutdownGracefully();
            }
        }
    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {
          String host = args[0];
           int port = Integer.parseInt(args[1]);
           int num = Integer.parseInt(args[2]);

           for(int i=0;i<num;i++){
                    try {
                                new HSFTCPClient(host, port).run();
                                Thread.sleep(100);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
           } 
    }
}

HSFClientInitializer 是:

public class HSFClientInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
           ChannelPipeline p = ch.pipeline();
            p.addLast("frameDecoder", new ProtobufVarint32FrameDecoder());
            p.addLast("protobufDecoder", new ProtobufDecoder(NetMessage.getDefaultInstance()));

            p.addLast("frameEncoder", new ProtobufVarint32LengthFieldPrepender());
            p.addLast("protobufEncoder", new ProtobufEncoder());

            p.addLast("handler", new HSFTCPClientHandler());
    }

}

HSFTCPClientHandler 是:

public class HSFTCPClientHandler extends SimpleChannelInboundHandler<NetMessage> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, NetMessage msg)
            throws Exception {
          if(msg==null){
              return;
          }
          int msgType = msg.getMessageType();
          switch (msgType) {
              case 200:

            break;
        }

    }


     @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {

           Channel ch = ctx.channel();

           ChannelFuture future=  ctx.newSucceededFuture().addListener(new ClientConnectListener());
        }


    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {

           ctx.fireChannelInactive();
           ctx.disconnect().addListener(new ClientDisConnectListener());
    }

}

ClientConnectListener 是:

public class ClientConnectListener implements ChannelFutureListener {

    @Override
    public void operationComplete(ChannelFuture future) throws Exception {
        Channel ch= future.channel();

        NetMessage.Builder msgBuilder = NetMessage.newBuilder();
        msgBuilder.setMessageType(100);

        System.out.println("-------client send netMsg ----------");
        ch.writeAndFlush(msgBuilder.build());

    }
}

ClientDisConnectListener 是:

public class ClientDisConnectListener implements ChannelFutureListener {

    @Override
    public void operationComplete(ChannelFuture future) throws Exception {
        System.out.println("-------  disconnect-----------");
    }

}

客户端jvm参数:

/usr/java/jdk1.7.0_40/bin/java -Xms4G -Xmx4G -XX:NewSize=3584m -XX:PermSize=64m -XX:SurvivorRatio=1 -XX:+UseParallelGC -XX:-UseAdaptiveSizePolicy -classpath "./bin:./lib/" com.test.protobuf.client.HSFTCPClient ..*.**(ip) 10007 10000

Linux info: Tasks: 374 total, 1 running, 373 sleeping, 0 stopped, 0 zombie Cpu0 : 0.3%us, 0.7%sy, 0.0%ni, 99.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu1 : 0.3%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu2 : 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu3 : 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu4 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu5 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu6 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu7 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 32865072k total, 2735996k used, 30129076k free, 345764k buffers Swap: 35110904k total, 0k used, 35110904k free, 1362400k cached jdk version: java version "1.7.0_40" Java(TM) SE Runtime Environment (build 1.7.0_40-b43) Java HotSpot(TM) 64-Bit Server VM (build 24.0-b56, mixed mode)

如何修复该错误？并调整客户端代码？

我真的希望Netty能够在一台服务器上保持至少5万个TCP连接。

Answer 1

这很有趣...您可以打开错误报告并添加如何重现它的信息吗？谢谢!

https://github.com/netty/netty/issues?state=open

经过更多研究，我找到了根本原因并为 JDK 提供了补丁。所以让它短路是一个 JDK 错误。

参见: http://mail.openjdk.java.net/pipermail/nio-dev/2013-September/002284.html