Kafka服务端NIO操作原理解析（二）

Kafka系列文章

基于Kafka2.1解读Producer原理
基于Kafka2.1解读Consumer原理
Kafka服务端NIO操作原理解析（一）

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前言

废话不多说，继续上一篇文章，我们继续基于Kafka3.7解读服务端的nio原理

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一、基本认知

可以看到Acceptor和Processor都是线程，所以实际Kafka服务端在启动（执行startup）方法之后，会基于一个Acceptor多个Processor的模式启动，并把这多个线程执行起来。

二、Acceptor的主体流程

对于Acceptor来说，主要就是通过selector监听accept事件，然后选择一个processor来进行后续操作

2.1 run方法源码

  /**
   * Accept loop that checks for new connection attempts
   */
  override def run(): Unit = {
   
   
    serverChannel.register(nioSelector, SelectionKey.OP_ACCEPT)
    try {
   
   
      while (shouldRun.get()) {
   
   
        try {
   
   
          acceptNewConnections()
          closeThrottledConnections()
        }
        catch {
   
   
          // We catch all the throwables to prevent the acceptor thread from exiting on exceptions due
          // to a select operation on a specific channel or a bad request. We don't want
          // the broker to stop responding to requests from other clients in these scenarios.
          case e: ControlThrowable => throw e
          case e: Throwable => error("Error occurred", e)
        }
      }
    } finally {
   
   
      debug("Closing server socket, selector, and any throttled sockets.")
      CoreUtils.swallow(serverChannel.close(), this, Level.ERROR)
      CoreUtils.swallow(nioSelector.close