ControllerEventManager¶

ControllerEventManager manages the event queue and the controller-event-thread (for event processing) for KafkaController.

Creating Instance¶

ControllerEventManager takes the following to be created:

• Controller ID (i.e. the broker.id of the broker)
• ControllerEventProcessor
• Time
• rateAndTimeMetrics
• eventQueueTimeTimeoutMs (default: 300000)

ControllerEventManager is created when:

• KafkaController is created

rateAndTimeMetrics¶

rateAndTimeMetrics: Map[ControllerState, KafkaTimer]

ControllerEventManager is given rateAndTimeMetrics that are KafkaTimers per ControllerState.

Performance Metrics¶

ControllerEventManager is a KafkaMetricsGroup and registers the following performance metrics in kafka.controller:type=ControllerEventManager group.

EventQueueSize¶

Number of QueuedEvents in the event queue

EventQueueTimeMs¶

Event Queue¶

ControllerEventManager creates a LinkedBlockingQueue (Java) of QueuedEvents.

Use EventQueueSize metric to monitor the depth of the queue.

The LinkedBlockingQueue is used to:

• put a ControllerEvent
• clearAndPut
• pollFromEventQueue

Emitting (Enqueuing) Controller Event¶

put(
  event: ControllerEvent): QueuedEvent

put creates a QueuedEvent with the input ControllerEvent and adds it to the end of the event queue.

put is used when:

• ControllerBrokerRequestBatch is requested to sendEvent
• ControllerEventManager is requested to clearAndPut
• KafkaController is doing its operation (and emits events)

Starting ControllerEventThread¶

start(): Unit

start requests the ControllerEventThread to start processing ControllerEvents.

start is used when:

• KafkaController is requested to start up

controller-event-thread¶

ControllerEventManager creates a ControllerEventThread when created.

The name of ControllerEventThread is controller-event-thread.

The ControllerEventThread is requested to start when start and runs until close.

ControllerState¶

ControllerEventManager is in one of the possible ControllerStates:

• Idle when ControllerEventManager is created and right after ControllerEventThread has finished processing a controller event

• State transitions happen per the requested state of the ControllerEvent being processed (while ControllerEventThread is processing controller events)

pollFromEventQueue¶

pollFromEventQueue(): QueuedEvent

pollFromEventQueue takes a QueuedEvent off the queue.

pollFromEventQueue is used when:

• ControllerEventThread is requested to doWork