- 在实际应用中broker可能因为机器，硬件，网络，进程自身等原因挂掉;
- 本章我们来看下一个broker挂掉后整个kafka集群会发生什么事情。
挂掉的broker不是集群的Controller
- 在Kafka集群建立过程分析和KafkaController分析6-Replica状态机我们讲过，
KafkaController组件中的ReplicaStateMachine对象在启动时会注册监听BrokerChangeListener事件;
- 当一个broker挂掉后，其在zk的
/brokers/ids下面的节点信息将被自动删除;
- ReplicaStateMachine
的BrokerChangeListener`将触发：
val curBrokerIds = currentBrokerList.map(_.toInt).toSet
val newBrokerIds = curBrokerIds -- controllerContext.liveOrShuttingDownBrokerIds
val newBrokerInfo = newBrokerIds.map(zkUtils.getBrokerInfo(_))
val newBrokers = newBrokerInfo.filter(_.isDefined).map(_.get)
val deadBrokerIds = controllerContext.liveOrShuttingDownBrokerIds -- curBrokerIds
controllerContext.liveBrokers = curBrokerIds.map(zkUtils.getBrokerInfo(_)).filter(_.isDefined).map(_.get)
newBrokers.foreach(controllerContext.controllerChannelManager.addBroker(_))
deadBrokerIds.foreach(controllerContext.controllerChannelManager.removeBroker(_))
if(newBrokerIds.size > 0)
controller.onBrokerStartup(newBrokerIds.toSeq)
if(deadBrokerIds.size > 0)
controller.onBrokerFailure(deadBrokerIds.toSeq)
- 从zk返回了当前的broker列表信息;
-
val deadBrokerIds = controllerContext.liveOrShuttingDownBrokerIds -- curBrokerIds获取到当前挂掉的broker ids;
- 更新
KafkaControllerContext.liveBrokers;
- 回调
KafkaController.onBrokerFailure(deadBrokerIds.toSeq);
- Broker挂掉的逻辑处理：
KafkaController.onBrokerFailure(deadBrokerIds.toSeq)
val deadBrokersSet = deadBrokers.toSet
val partitionsWithoutLeader = controllerContext.partitionLeadershipInfo.filter(partitionAndLeader =>
deadBrokersSet.contains(partitionAndLeader._2.leaderAndIsr.leader) &&
!deleteTopicManager.isTopicQueuedUpForDeletion(partitionAndLeader._1.topic)).keySet
partitionStateMachine.handleStateChanges(partitionsWithoutLeader, OfflinePartition)
partitionStateMachine.triggerOnlinePartitionStateChange()
var allReplicasOnDeadBrokers = controllerContext.replicasOnBrokers(deadBrokersSet)
val activeReplicasOnDeadBrokers = allReplicasOnDeadBrokers.filterNot(p => deleteTopicManager.isTopicQueuedUpForDeletion(p.topic))
replicaStateMachine.handleStateChanges(activeReplicasOnDeadBrokers, OfflineReplica)
- 先处理
KafkacontrollerContext.partitionLeadershipInfo(这里面保存着当前所有topic的各个partition的leader相关信息)，筛选出所有leader为当前挂掉的broker的TopicAndPartiton保存到partitionsWithoutLeader中；
- 将
partitionsWithoutLeader中的partition状态转换成OfflinePartition;
- 通过
partitionStateMachine.triggerOnlinePartitionStateChange()对于上面2中OfflinePartition状态的partition进行重新选主(PartitonStateMachine.electLeaderForPartition);
- 产生新的LeaderAndIsr Request发送到topic相关的replicas上;
- 产生新的UpdateMetadata Request发送到各broker上;
-
replicaStateMachine.handleStateChanges(activeReplicasOnDeadBrokers, OfflineReplica): 将相应的replica状态转换为OfflineReplica;
- 在上面6中的状态转换时会调用
controller.removeReplicaFromIsr(topic, partition, replicaId), 生成新的LeaderAndIsr Request, 真正broker挂掉这种情况个人感觉这个调用是多余的,因为在上面的3中新的LeaderAndIsr Request已经发送;
