IllegalStateException 主题、分区和模式的订阅是互斥的

Question

需要从 Kafka 主题的特定偏移量获取消息

导致 IllegalStateException 异常卡在assign()

如果我不使用assign()，那么消费者不会执行搜索，因为这是一个惰性操作

实际目的：需要从预先确定的偏移量到结束迭代主题中的消息。该预先确定的偏移量计算为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();
}

涉及的其余相关代码

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);
}

消费者创造

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;
}   

例外

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)

Answer 1

不能混合分配manual和automatic分区分配。您应该使用KafkaConsumer::subscribe或，KafkaConsumer::assign但不能同时使用两者。

如果在致电后KafkaConsumer::subscribe您想切换到manual方法，您应该首先致电KafkaConsumer::unsubscribe。

根据https://kafka.apache.org/10/javadoc/org/apache/kafka/clients/consumer/KafkaConsumer.html

请注意，不可能将手动分区分配（即使用分配）与通过主题订阅的动态分区分配（即使用订阅）混合在一起。