Implementation:Apache Kafka CoordinatorRuntime ScheduleLoadOperation

Knowledge Sources	Apache Kafka
Domains	Distributed_Systems, Coordinator_Framework
Last Updated	2026-02-09 12:00 GMT

Overview

Concrete tool for scheduling coordinator partition loading provided by the CoordinatorRuntime framework.

Description

The scheduleLoadOperation method on CoordinatorRuntime creates or reuses a CoordinatorContext for the given topic-partition and initiates state loading. It schedules an internal operation that checks the partition epoch, transitions the state to LOADING if appropriate, and triggers the CoordinatorLoaderImpl to replay records from the partition log.

Usage

Called by the Kafka server when a broker becomes the leader for a coordinator topic-partition (e.g., __consumer_offsets or __share_group_state).

Code Reference

Source Location

• Repository: Apache Kafka
• File: coordinator-common/src/main/java/org/apache/kafka/coordinator/common/runtime/CoordinatorRuntime.java
• Lines: L2267-2311

Signature

public void scheduleLoadOperation(
    TopicPartition tp,
    int partitionEpoch
)

Import

import org.apache.kafka.coordinator.common.runtime.CoordinatorRuntime;
import org.apache.kafka.common.TopicPartition;

I/O Contract

Inputs

Name	Type	Required	Description
tp	TopicPartition	Yes	The coordinator's topic-partition
partitionEpoch	int	Yes	The leader epoch of the partition

Outputs

Name	Type	Description
CoordinatorContext	internal	Created or reused context for the partition
State transition	void	Context transitions to LOADING state

Usage Examples

// Called when broker becomes leader for __consumer_offsets-0
coordinatorRuntime.scheduleLoadOperation(
    new TopicPartition("__consumer_offsets", 0),
    42  // leader epoch
);

Related Pages

Implements Principle

• Principle:Apache_Kafka_Partition_Load_Scheduling
• Environment:Apache_Kafka_JVM_Runtime_Environment