我的网络程序有时会发生异常，例如“对等连接重置”

Question

我正在使用netty-all-4.1.0.Final.jar编码一个http服务器，而服务器在侦听时，有时会发生“对等连接重置”，详细信息如下：

Connection reset by peer
java.io.IOException: Connection reset by peer
    at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
    at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
    at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
    at sun.nio.ch.IOUtil.read(IOUtil.java:192)
    at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380)
    at io.netty.buffer.PooledUnsafeDirectByteBuf.setBytes(PooledUnsafeDirectByteBuf.java:288)
    at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1098)
    at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:350)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:112)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:544)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:485)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:399)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:371)
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:742)
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:145)
    at java.lang.Thread.run(Thread.java:748)

这是我的主要服务器代码：

public static void main(String[] args) throws InterruptedException {
    EventLoopGroup bossGroup = new NioEventLoopGroup();
    EventLoopGroup workerGroup = new NioEventLoopGroup();
    try {
        ServerBootstrap b = new ServerBootstrap();
        b.group(bossGroup, workerGroup)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch) throws Exception {
                        ChannelPipeline pipeline = ch.pipeline();
                        pipeline.addLast(new HttpServerCodec());
                        //将同一个http请求的内容组装到一起，调用一次handler
                        pipeline.addLast(new HttpObjectAggregator(65536));
                        pipeline.addLast(new HttpServerHandler());
                    }
                });
        int port = ConfUtils.port;
        ChannelFuture f = b.bind(port).sync();
        logger.info("start lisner-------port is {}",port);
        f.channel().closeFuture().sync();
    } catch(Exception e){
     logger.error(e.getMessage(),e);
    }
    finally {
        workerGroup.shutdownGracefully();
        bossGroup.shutdownGracefully();
    }
}

这是我的处理程序类：

  @Override
 public void channelRead(ChannelHandlerContext ctx, Object msg) {

  if(msg instanceof FullHttpRequest){
   try{
    logger.info("accept http msg!");
    FullHttpRequest fullHttpRequest = (FullHttpRequest)msg;
    ProcessMsg.dealMsg(fullHttpRequest);
    logger.info("full header is {}",fullHttpRequest);
    String responseHtml = "response from server!";
            byte[] responseBytes = responseHtml.getBytes("UTF-8");
            int contentLength = responseBytes.length;
   FullHttpResponse response = new 
   DefaultFullHttpResponse(HttpVersion.HTTP_1_1, 
   HttpResponseStatus.OK,Unpooled.wrappedBuffer(responseBytes));
   response.headers().set("Content-Type", "text/html; charset=utf-8");
            response.headers().set("Content-Length", Integer.toString(contentLength));
            Thread.sleep(1000 * 5);
   ctx.writeAndFlush(response);
   ctx.flush();
   logger.info("response from server!");
  }catch(Exception e){
   logger.error(e.getMessage(),e);
  }
    }
 else{
  logger.info("this is not http request");
 }
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
 LoggerFactory.getLogger("excplog").error(cause.getMessage(),cause);
    ctx.close();
}

}

它并不总是发生，有时是发生，而大多数时候却没有，我们找不到关于请求的任何问题