错误信息如下：
07/01/20 06:15:37:037 CST] main ERROR transport.AbstractCodec: Data length too large: 39889057, max payload: 8388608, channel: NettyChannel [channel=[id: 0x5c465e9f, /192.168.140.29:3842 => /192.168.140.29:20880]] java.io.IOException: Data length too large: 39889057, max payload: 8388608, channel: NettyChannel [channel=[id: 0x5c465e9f, /192.168.140.29:3842 => /192.168.140.29:20880]] at com.alibaba.dubbo.remoting.transport.AbstractCodec.checkPayload(AbstractCodec.java:49) at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.encodeRequest(ExchangeCodec.java:242) at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.encode(ExchangeCodec.java:75) at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCountCodec.encode(DubboCountCodec.java:39) at com.alibaba.dubbo.remoting.transport.netty.NettyCodecAdapter$InternalEncoder.encode(NettyCodecAdapter.java:81) at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.doEncode(OneToOneEncoder.java:66) at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:59) at org.jboss.netty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:591) at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendDownstream(DefaultChannelPipeline.java:784) at org.jboss.netty.channel.SimpleChannelHandler.writeRequested(SimpleChannelHandler.java:292) at com.alibaba.dubbo.remoting.transport.netty.NettyHandler.writeRequested(NettyHandler.java:99) at org.jboss.netty.channel.SimpleChannelHandler.handleDownstream(SimpleChannelHandler.java:254) at org.jboss.netty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:591) at org.jboss.netty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:582) at org.jboss.netty.channel.Channels.write(Channels.java:704) at org.jboss.netty.channel.Channels.write(Channels.java:671) at org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:348) at com.alibaba.dubbo.remoting.transport.netty.NettyChannel.send(NettyChannel.java:98) at com.alibaba.dubbo.remoting.transport.AbstractClient.send(AbstractClient.java:270) at com.alibaba.dubbo.remoting.transport.AbstractPeer.send(AbstractPeer.java:51) at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeChannel.request(HeaderExchangeChannel.java:112) at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeClient.request(HeaderExchangeClient.java:91) at com.alibaba.dubbo.rpc.protocol.dubbo.ReferenceCountExchangeClient.request(ReferenceCountExchangeClient.java:81) at com.alibaba.dubbo.rpc.protocol.dubbo.DubboInvoker.doInvoke(DubboInvoker.java:96) at com.alibaba.dubbo.rpc.protocol.AbstractInvoker.invoke(AbstractInvoker.java:144) at com.alibaba.dubbo.rpc.listener.ListenerInvokerWrapper.invoke(ListenerInvokerWrapper.java:74) at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.protocol.dubbo.filter.FutureFilter.invoke(FutureFilter.java:53) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.filter.ConsumerContextFilter.invoke(ConsumerContextFilter.java:48) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53) at com.alibaba.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:77) at com.alibaba.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:227) at com.alibaba.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:72) at com.alibaba.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:52) at com.alibaba.dubbo.common.bytecode.proxy0.getData(proxy0.java) at com.dubbo.demo.DemoService.Consumer.main(Consumer.java:38)
调大 payload 即可解决相关问题
解决方案1：
怎么解决，在服务提供提供者， 添加
<dubbo:protocol name="dubbo" port="20880" payload="39889058"/>
39889058 > 39889057 可以发现是生效的，不再爆出异常了
解决方案2：
dubbo.properties中添加一行 dubbo.protocol.dubbo.payload=39889058
但是要强调的是，一般是不建议使用这种方式。
Dubbo 缺省协议采用单一长连接和 NIO 异步通讯，适合于小数据量大并发的服务调用，以及服务消费者机器数远大于服务提供者机器数的情况。Dubbo缺省协议不适合传送大数据量的服务，比如传文件，传视频等，除非请求量很低。
