[英]How to implement “Exactly once” kafka consumer using Apache Kafka?
我們有一個應用程序,它使用來自 Kafka 主題(3 個分區)的消息並豐富數據並將記錄保存在 DB(Spring JPA)中,然后將消息發布到另一個 kafka 主題(在同一個代理上),所有這些都由使用 Camel 2.4.1 和 Spring 啟動 2.1.7.RELEASE。
我們想為 kafka 消費者-生產者組合實現“exactly-once”語義。
消費者設置:
autoOffsetReset: earliest
autoCommitEnable: false
allowManualCommit: true
breakOnFirstError: true
group.id : CONSUMER.GROUP.ID
count: 3
max.poll.records = 1 # rollback when message processing fails.
生產者設置:
idempotence: true
transactionIdPrefix: txn-prefix-id
豆接線:
@Bean
SpringTransactionPolicy springTransactionPolicy() throws Exception {
SpringTransactionPolicy txRequired = new SpringTransactionPolicy();
txRequired.setTransactionManager(transactionManager());
txRequired.setPropagationBehaviorName("PROPAGATION_REQUIRED");
return txRequired;
}
@Bean
public DefaultKafkaProducerFactory<byte[], byte[]> producerFactory() {
DefaultKafkaProducerFactory<byte[], byte[]> defaultKafkaProducerFactory = new DefaultKafkaProducerFactory<byte[], byte[]>(
kafkaConfigs());
// enable transaction manager
defaultKafkaProducerFactory.setTransactionIdPrefix(transactionIdPrefix);
return defaultKafkaProducerFactory;
}
@Bean
@Primary
public ChainedKafkaTransactionManager<byte[], byte[]> transactionManager() throws Exception {
return new ChainedKafkaTransactionManager<>(kafkaTransactionManager(),jpaTransactionManager());
}
@Bean
public PlatformTransactionManager kafkaTransactionManager() {
KafkaTransactionManager<byte[], byte[]> kafkaTransactionManager = new KafkaTransactionManager<>(producerFactory);
kafkaTransactionManager.setTransactionSynchronization(AbstractPlatformTransactionManager.SYNCHRONIZATION_ON_ACTUAL_TRANSACTION);
kafkaTransactionManager.setRollbackOnCommitFailure(true);
return kafkaTransactionManager;
}
@Bean
JpaTransactionManager jpaTransactionManager() {
JpaTransactionManager transactionManager = new JpaTransactionManager();
transactionManager.setRollbackOnCommitFailure(true);
return transactionManager;
}
駱駝路線:
public RoutesBuilder inboundRoute() {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
//Common error handler
onException(UnsupportedMessageTypeException.class).
maximumRedeliveries(redeliveryCount).
handled(true).
bean(ExceptionPropagatorProcessor.class, "process").
bean(manualCommitProcessor).
end();
onException(AppRuntimeException.class).
maximumRedeliveries(redeliveryCount).
bean(ExceptionPropagatorProcessor.class, "process")
end();
onException(RetryExhaustedException.class).
maximumRedeliveries(0).// No retry for this exception
handled(true).
bean(ExceptionPropagatorProcessor.class, "process").
bean(kafkaManualCommitProcessor).
end();
from("kafka:inboundTopic").
routeId("consume-msg").
transacted("springTransactionPolicy").
bean(transactionBeginProcessor).
//check if this is a retry scenario, the max retry count reached then throw RetryExhaustedException.
bean(retryEvaluationProcessor).
bean(enrichProcessor). // publish kafka messages
bean(persistenceProcessor).
bean(transactionEndProcessor). // publish kafka messages
bean(manualCommitProcessor);
但是當出現異常處理場景時,我們無法讓 kafka 生產者提交消息。 我缺少什么,正確的方法是什么?
您似乎正在使用 Spring Kafka 並且他們的 KafkaTransactionManager 不是真正的支持 XA 的事務管理器(請參閱他們的文檔以了解限制),因此您不能將它用於 Kafka 和 JDBC 數據庫等的回滾。
並且 camel-kafka 不支持 Kafka 事務(目前)。 我創建了一張票: https://issues.apache.org/jira/browse/CAMEL-15016
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