netty优化学习积累+++++++

一、

c/s-Handler在需要发送消息时，不一定必须调用writeandFlush()，如果对于一些零碎的消息都writeAndFlush(),那么多次频繁的调用对应多次的syscall系统调用，如何减少系统调用提高效率？

write()函数，对于多次要发送的零碎的消息都采用write()函数，这样只会把消息gather汇聚起来，放到缓冲区中，

最后一个flush()函数，会将缓冲区中汇聚的多方消息全部整合发送，减少了系统调用syscall.

https://stackoverflow.com/questions/27498428/implementing-group-flush-in-server-side-netty-handler

二、

1) If the client is only interested in sending, not in receiving, you can always disable reading from channel like below

channel.setReadable(false);

2) You can increase the throughput very easily by having multiple client channels per client, and also it can scale too.

3) and you can do following tweaks to improve the performance in general (for read/ write)

• Its better to have a SEDA like pipline by adding a EXecutionHandler with OrderdMemoryAwareThreadPoolExecutor, (with min, max channel memory with optimal value)

  bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
      @Override
      public ChannelPipeline getPipeline() throws Exception {
          return Channels.pipeline(
                  executionHandler1,//sharable
                  new MessageDecoderHandler(),
                  new MessageEncoderHandler(),
                  executionHandler2,//sharable
                  new BusinessLogicHandler1(),
                  new BusinessLogicHandler2());
      }
  });

• Setting the writeBufferHighWaterMark of the channel to optimal value (Make sure that setting a big value will not create congestion)

  bootstrap.setOption("writeBufferHighWaterMark", 10 * 64 * 1024);

• Setting the SO_READ, SO_WRITE buffer size

  bootstrap.setOption("sendBufferSize", 1048576); bootstrap.setOption("receiveBufferSize", 1048576);

• Enabling the TCP No delay

  bootstrap.setOption("tcpNoDelay", true);

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  • 三、
  • netty为什么去掉支持aio
  • https://blog.csdn.net/lirenzuo/article/details/79465975
  • 四、
  • windows iocp(input/output completion port中文：io完成端口)支持aio,
  • linux没有成熟的支持网络aio的底层实现，目前epoll多路复用已经满足性能需求。
  • https://www.quora.com/Why-doesnt-Linux-have-a-system-like-IOCP-or-Rio-does

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