kafka broker启动

通过bin下面的kafka-server-start.sh 可以启动一个broker，命令如下：nohup ./kafka-server-start.sh config/server.properties &
这个脚本主要是调用kafka.kafka 这个类
exec $base_dir/kafka-run-class.sh $EXTRA_ARGS kafka.Kafka "$@"
与之对应的是停止一个broker对应的脚本是kafka-server-stop.sh
SIGNAL=${SIGNAL:-TERM}
PIDS=$(ps ax | grep -i 'kafka\.Kafka' | grep java | grep -v grep | awk '{print $1}')

if [ -z "$PIDS" ]; then
  echo "No kafka server to stop"
  exit 1
else
  kill -s $SIGNAL $PIDS
fi
这个脚本就是通过ps ax 查找到kafka的进程后，然后通过kill 命令将这个进程杀死
我们首先看看kafka这个类
core/src/main/scala/kafka/Kafka.scala

def main(args: Array[String]): Unit = {
    try {
      val serverProps = getPropsFromArgs(args)
      val kafkaServerStartable = KafkaServerStartable.fromProps(serverProps)

      try {
        if (!OperatingSystem.IS_WINDOWS && !Java.isIbmJdk)
          new LoggingSignalHandler().register()
      } catch {
        case e: ReflectiveOperationException =>
          warn("Failed to register optional signal handler that logs a message when the process is terminated " +
            s"by a signal. Reason for registration failure is: $e", e)
      }

      // attach shutdown handler to catch terminating signals as well as normal termination
      Runtime.getRuntime().addShutdownHook(new Thread("kafka-shutdown-hook") {
        override def run(): Unit = kafkaServerStartable.shutdown()
      })
#这里调用kafkaServerStartable 的startup函数来启动broker
      kafkaServerStartable.startup()
      kafkaServerStartable.awaitShutdown()
    }

KafkaServerStartable 这个类的starup和shutdonw函数如下：
\core\src\main\scala\kafka\server\KafkaServerStartable.scala

class KafkaServerStartable(val staticServerConfig: KafkaConfig, reporters: Seq[KafkaMetricsReporter]) extends Logging {
  private val server = new KafkaServer(staticServerConfig, kafkaMetricsReporters = reporters)

  def this(serverConfig: KafkaConfig) = this(serverConfig, Seq.empty)

  def startup() {
#这里有调用KafkaServer的startup函数来启动broker
    try server.startup()
    catch {
      case _: Throwable =>
        // KafkaServer.startup() calls shutdown() in case of exceptions, so we invoke `exit` to set the status code
        fatal("Exiting Kafka.")
        Exit.exit(1)
    }
  }

  def shutdown() {
    try server.shutdown()
    catch {
      case _: Throwable =>
        fatal("Halting Kafka.")
        // Calling exit() can lead to deadlock as exit() can be called multiple times. Force exit.
        Exit.halt(1)
    }
  }

KafkaServer.scala 的startup函数如下：
core\src\main\scala\kafka\server\KafkaServer.scala

  def startup() {
    try {
      info("starting")

        quotaManagers = QuotaFactory.instantiate(config, metrics, time, threadNamePrefix.getOrElse(""))
        notifyClusterListeners(kafkaMetricsReporters ++ metrics.reporters.asScala)

        logDirFailureChannel = new LogDirFailureChannel(config.logDirs.size)
这个类会启动很多manager，下面这行就可以看到logManager 是从kafkaserver中启动的
        /* start log manager */
        logManager = LogManager(config, initialOfflineDirs, zkClient, brokerState, kafkaScheduler, time, brokerTopicStats, logDirFailureChannel)
        logManager.startup()
}