Need to fetch messages from a Kafka topic, from a particular offset
Stuck cause of IllegalStateException exception at assign()
If I do not use assign() , then the consumer does not perform seek, as that being a Lazy operation
Actual purpose: Need to iterate messages at topic from a pre-decided offset till end. This pre-decided offset is calculated at markOffset()
static void fetchMessagesFromMarkedOffset() {
Consumer<Long, String> consumer = ConsumerCreator.createConsumer();
consumer.assign(set); // <---- Exception at this place
map.forEach((k,v) -> {
consumer.seek(k, v-3);
});
ConsumerRecords<Long, String> consumerRecords = consumer.poll(100);
consumerRecords.forEach(record -> {
System.out.println("Record Key " + record.key());
System.out.println("Record value " + record.value());
System.out.println("Record partition " + record.partition());
System.out.println("Record offset " + record.offset());
});
consumer.close();
}
Rest of concerned code involved
public static Set<TopicPartition> set;
public static Map<TopicPartition, Long> map;
static void markOffset() {
Consumer<Long, String> consumer = ConsumerCreator.createConsumer();
consumer.poll(100);
set = consumer.assignment();
map = consumer.endOffsets(set);
System.out.println("Topic Partitions: " + set);
System.out.println("End Offsets: " + map);
}
Consumer Creation
private Consumer createConsumer(String topicName) {
final Properties props = new Properties();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
props.put(ConsumerConfig.GROUP_ID_CONFIG, "capacity-service-application");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, LongDeserializer.class.getName());
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "false");
props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
final Consumer consumer = new KafkaConsumer(props);
consumer.subscribe(Collections.singletonList(topicName));
return consumer;
}
Exception
Exception in thread "main" java.lang.IllegalStateException: Subscription to topics, partitions and pattern are mutually exclusive
at org.apache.kafka.clients.consumer.internals.SubscriptionState.setSubscriptionType(SubscriptionState.java:104)
at org.apache.kafka.clients.consumer.internals.SubscriptionState.assignFromUser(SubscriptionState.java:157)
at org.apache.kafka.clients.consumer.KafkaConsumer.assign(KafkaConsumer.java:1064)
at com.gaurav.kafka.App.fetchMessagesFromMarkedOffset(App.java:44)
at com.gaurav.kafka.App.main(App.java:30)