Kafka的初始化啟動流程

• 由KafkaServer::startup來負責;
• KafkaServer::startup主要是創建并啟動各種Manager;
• 上圖:

kafkaserver_startup.png

• KafkaHealthcheck: core/src/main/scala/kafka/server/KafkaHealthcheck.scala,其作用是在broker info注冊到zk的/brokers/id路徑下, 且監聽zk的session expiration事件,觸發時重新注冊;

• 上圖中的各個啟動的組件我們慢慢都會介紹到, 先從請求的接收與響應開始~~~

請求處理

• SocketServer: 負責處理網絡連接, 數據的接收和發送, 其中的RequestChannel負責向應用層轉遞請求,也負責把應用層的response傳回網絡層后發送出去;
  詳細見:Kafka源碼分析-網絡層-1 Kafka源碼分析-網絡層-2 Kafka源碼分析-網絡層-3
• KafkaRequestHandlerPool: 線程池, 每個線程里跑一個KafkaRequestHandler
• KafkaRequestHandler: 循環調用RequestChannel::receiveRequest來poll到新的request交給KafkaApis處理;
• KafkaApis: 處理request的分發

request.requestId match {
        case RequestKeys.ProduceKey => handleProducerRequest(request)
        case RequestKeys.FetchKey => handleFetchRequest(request)
        case RequestKeys.OffsetsKey => handleOffsetRequest(request)
        case RequestKeys.MetadataKey => handleTopicMetadataRequest(request)
        case RequestKeys.LeaderAndIsrKey => handleLeaderAndIsrRequest(request)
        case RequestKeys.StopReplicaKey => handleStopReplicaRequest(request)
        case RequestKeys.UpdateMetadataKey => handleUpdateMetadataRequest(request)
        case RequestKeys.ControlledShutdownKey => handleControlledShutdownRequest(request)
        case RequestKeys.OffsetCommitKey => handleOffsetCommitRequest(request)
        case RequestKeys.OffsetFetchKey => handleOffsetFetchRequest(request)
        case RequestKeys.GroupCoordinatorKey => handleGroupCoordinatorRequest(request)
        case RequestKeys.JoinGroupKey => handleJoinGroupRequest(request)
        case RequestKeys.HeartbeatKey => handleHeartbeatRequest(request)
        case RequestKeys.LeaveGroupKey => handleLeaveGroupRequest(request)
        case RequestKeys.SyncGroupKey => handleSyncGroupRequest(request)
        case RequestKeys.DescribeGroupsKey => handleDescribeGroupRequest(request)
        case RequestKeys.ListGroupsKey => handleListGroupsRequest(request)
        case requestId => throw new KafkaException("Unknown api code " + requestId

上圖:

kafkaapis.png

下篇我們開始KafkaController分析-選主和Failover

Kafka源碼分析-匯總