报错信息如下：
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)解决方案：
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
参考资料：
http://dubbo.apache.org/zh-cn/docs/user/references/xml/dubbo-protocol.html
