问题
I read a ton of Gary Russell answers and posts, but didn't find actual solution for the common use-case for synchronization of the sequence below:
recieve from topic A => save to DB via Spring-data => send to topic B
As i understand properly: there is no guarantee for fully atomic processing in that case and i need to deal with messages deduplication on the client side, but the main issue is that ChainedKafkaTransactionManager doesn't synchronize with JpaTransactionManager (see @KafkaListener below)
Kafka config:
@Production
@EnableKafka
@Configuration
@EnableTransactionManagement
public class KafkaConfig {
private static final Logger log = LoggerFactory.getLogger(KafkaConfig.class);
@Bean
public ConsumerFactory<String, byte[]> commonConsumerFactory(@Value("${kafka.broker}") String bootstrapServer) {
Map<String, Object> props = new HashMap<>();
props.put(BOOTSTRAP_SERVERS_CONFIG, bootstrapServer);
props.put(AUTO_OFFSET_RESET_CONFIG, 'earliest');
props.put(SESSION_TIMEOUT_MS_CONFIG, 10000);
props.put(ENABLE_AUTO_COMMIT_CONFIG, false);
props.put(MAX_POLL_RECORDS_CONFIG, 10);
props.put(MAX_POLL_INTERVAL_MS_CONFIG, 17000);
props.put(FETCH_MIN_BYTES_CONFIG, 1048576);
props.put(FETCH_MAX_WAIT_MS_CONFIG, 1000);
props.put(ISOLATION_LEVEL_CONFIG, 'read_committed');
props.put(KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
props.put(VALUE_DESERIALIZER_CLASS_CONFIG, ByteArrayDeserializer.class);
return new DefaultKafkaConsumerFactory<>(props);
}
@Bean
public ConcurrentKafkaListenerContainerFactory<String, byte[]> kafkaListenerContainerFactory(
@Qualifier("commonConsumerFactory") ConsumerFactory<String, byte[]> consumerFactory,
@Qualifier("chainedKafkaTM") ChainedKafkaTransactionManager chainedKafkaTM,
@Qualifier("kafkaTemplate") KafkaTemplate<String, byte[]> kafkaTemplate,
@Value("${kafka.concurrency:#{T(java.lang.Runtime).getRuntime().availableProcessors()}}") Integer concurrency
) {
ConcurrentKafkaListenerContainerFactory<String, byte[]> factory = new ConcurrentKafkaListenerContainerFactory<>();
factory.getContainerProperties().setMissingTopicsFatal(false);
factory.getContainerProperties().setTransactionManager(chainedKafkaTM);
factory.setConsumerFactory(consumerFactory);
factory.setBatchListener(true);
var arbp = new DefaultAfterRollbackProcessor<String, byte[]>(new FixedBackOff(1000L, 3));
arbp.setCommitRecovered(true);
arbp.setKafkaTemplate(kafkaTemplate);
factory.setAfterRollbackProcessor(arbp);
factory.setConcurrency(concurrency);
factory.afterPropertiesSet();
return factory;
}
@Bean
public ProducerFactory<String, byte[]> producerFactory(@Value("${kafka.broker}") String bootstrapServer) {
Map<String, Object> configProps = new HashMap<>();
configProps.put(BOOTSTRAP_SERVERS_CONFIG, bootstrapServer);
configProps.put(BATCH_SIZE_CONFIG, 16384);
configProps.put(ENABLE_IDEMPOTENCE_CONFIG, true);
configProps.put(KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
configProps.put(VALUE_SERIALIZER_CLASS_CONFIG, ByteArraySerializer.class);
var kafkaProducerFactory = new DefaultKafkaProducerFactory<String, byte[]>(configProps);
kafkaProducerFactory.setTransactionIdPrefix('kafka-tx-');
return kafkaProducerFactory;
}
@Bean
public KafkaTemplate<String, byte[]> kafkaTemplate(@Qualifier("producerFactory") ProducerFactory<String, byte[]> producerFactory) {
return new KafkaTemplate<>(producerFactory);
}
@Bean
public KafkaTransactionManager kafkaTransactionManager(@Qualifier("producerFactory") ProducerFactory<String, byte[]> producerFactory) {
KafkaTransactionManager ktm = new KafkaTransactionManager<>(producerFactory);
ktm.setTransactionSynchronization(SYNCHRONIZATION_ON_ACTUAL_TRANSACTION);
return ktm;
}
@Bean
public ChainedKafkaTransactionManager chainedKafkaTM(JpaTransactionManager jpaTransactionManager,
KafkaTransactionManager kafkaTransactionManager) {
return new ChainedKafkaTransactionManager(kafkaTransactionManager, jpaTransactionManager);
}
@Bean(name = "transactionManager")
public JpaTransactionManager transactionManager(EntityManagerFactory em) {
return new JpaTransactionManager(em);
}
}
Kafka listener:
@KafkaListener(groupId = "${group.id}", idIsGroup = false, topics = "${topic.name.import}")
public void consume(List<byte[]> records, @Header(KafkaHeaders.OFFSET) Long offset) {
for (byte[] record : records) {
// cause infinity rollback (perhaps due to batch listener)
if (true)
throw new RuntimeExcetion("foo");
// spring-data storage with @Transactional("chainedKafkaTM"), since Spring-data can't determine TM among transactionManager, chainedKafkaTM, kafkaTransactionManager
var result = storageService.persist(record);
kafkaTemplate.send(result);
}
}
Spring-kafka version: 2.3.3 Spring-boot version: 2.2.1
What is a proper way to implement such use-case ? Spring-kafka documentation limited only to small/specific examples.
P.s. when i'm using @Transactional(transactionManager = "chainedKafkaTM", rollbackFor = Exception.class) on @KafkaListener method i am facing endless cyclic rollback, however FixedBackOff(1000L, 3L) is set.
EDIT: i'm planning to achieve max affordable synchronization between listener, producer and database with configurable retries num.
EDIT: Code snippets above edited with respect to advised configuration. Using ARBP doesn't solve infinity rollback cycle for me, since the first statement's predicate is always false (SeekUtils.doSeeks):
DefaultAfterRollbackProcessor
...
@Override
public void process(List<ConsumerRecord<K, V>> records, Consumer<K, V> consumer, Exception exception,
boolean recoverable) {
if (SeekUtils.doSeeks(((List) records), consumer, exception, recoverable,
getSkipPredicate((List) records, exception), LOGGER)
&& isCommitRecovered() && this.kafkaTemplate != null && this.kafkaTemplate.isTransactional()) {
ConsumerRecord<K, V> skipped = records.get(0);
this.kafkaTemplate.sendOffsetsToTransaction(
Collections.singletonMap(new TopicPartition(skipped.topic(), skipped.partition()),
new OffsetAndMetadata(skipped.offset() + 1)));
}
}
It is worth saying that there is no active transaction in Kafka Consumer method (TransactionSynchronizationManager.isActualTransactionActive()).
回答1:
What makes you think it's not synchronized? You really don't need @Transactional since the container will start both transactions.
You shouldn't use a SeekToCurrentErrorHandler with transactions because that occurs within the transaction. Configure the after rollback processor instead. The default ARBP uses a FixedBackOff(0L, 9) (10 attempts).
This works fine for me; and stops after 4 delivery attempts:
@SpringBootApplication
public class So58804826Application {
public static void main(String[] args) {
SpringApplication.run(So58804826Application.class, args);
}
@Bean
public JpaTransactionManager transactionManager() {
return new JpaTransactionManager();
}
@Bean
public ChainedKafkaTransactionManager<?, ?> chainedTxM(JpaTransactionManager jpa,
KafkaTransactionManager<?, ?> kafka) {
kafka.setTransactionSynchronization(SYNCHRONIZATION_ON_ACTUAL_TRANSACTION);
return new ChainedKafkaTransactionManager<>(kafka, jpa);
}
@Autowired
private Saver saver;
@KafkaListener(id = "so58804826", topics = "so58804826")
public void listen(String in) {
System.out.println("Storing: " + in);
this.saver.save(in);
}
@Bean
public NewTopic topic() {
return TopicBuilder.name("so58804826")
.partitions(1)
.replicas(1)
.build();
}
@Bean
public ApplicationRunner runner(KafkaTemplate<String, String> template) {
return args -> {
// template.executeInTransaction(t -> t.send("so58804826", "foo"));
};
}
}
@Component
class ContainerFactoryConfigurer {
ContainerFactoryConfigurer(ConcurrentKafkaListenerContainerFactory<?, ?> factory,
ChainedKafkaTransactionManager<?, ?> tm) {
factory.getContainerProperties().setTransactionManager(tm);
factory.setAfterRollbackProcessor(new DefaultAfterRollbackProcessor<>(new FixedBackOff(1000L, 3)));
}
}
@Component
class Saver {
@Autowired
private MyEntityRepo repo;
private final AtomicInteger ids = new AtomicInteger();
@Transactional("chainedTxM")
public void save(String in) {
this.repo.save(new MyEntity(in, this.ids.incrementAndGet()));
throw new RuntimeException("foo");
}
}
I see "Participating in existing transaction" from both TxMs.
and with @Transactional("transactionManager"), I just get it from the JPATm, as one would expect.
EDIT
There is no concept of "recovery" for a batch listener - the framework has no idea which record in the batch needs to be skipped. In 2.3, we added a new feature for batch listeners when using MANUAL ack modes.
See Committing Offsets.
Starting with version 2.3, the Acknowledgment interface has two additional methods nack(long sleep) and nack(int index, long sleep). The first one is used with a record listener, the second with a batch listener. Calling the wrong method for your listener type will throw an IllegalStateException.
When using a batch listener, you can specify the index within the batch where the failure occurred. When
nack()is called, offsets will be committed for records before the index and seeks are performed on the partitions for the failed and discarded records so that they will be redelivered on the next poll(). This is an improvement over the SeekToCurrentBatchErrorHandler, which can only seek the entire batch for redelivery.
However, the failed record will still be replayed indefinitely.
You could keep track of the record that keeps failing and nack index + 1 to skip over it.
However, since your JPA tx has rolled back; this won't work for you.
With batch listener's you must handle problems with batches in your listener code.
来源：https://stackoverflow.com/questions/58804826/spring-kafka-chainedkafkatransactionmanager-doesnt-synchronize-with-jpa-spring