CODEWITHSUNDEEP
javaapache-kafkakafka-consumer-api
jelmew
jelmew

Reputation: 583

Kafka consumer returns no records

I am trying to makea small PoC with Kafka. However, when making the consumer in java, this consumer gets no messages. Even though when I fire up a kafka-console-consumer.sh with the same url/topic, I do get messages. Does anyone know what I might do wrong? This code is called by a GET API.

public List<KafkaTextMessage> receiveMessages() {
    log.info("Retrieving messages from kafka");
    val props = new Properties();
    // See https://kafka.apache.org/documentation/#consumerconfigs
    props.put("bootstrap.servers", "my-cluster-kafka-bootstrap:9092");
    //props.put("client.id", "my-topic consumer");
    props.put("group.id", "test");
    props.put("enable.auto.commit", "false");
    props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
    props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
    ImmutableList.Builder<KafkaTextMessage> builder;
    try (KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props)) {
        consumer.subscribe(Collections.singletonList(TEXT_MESSAGE_TOPIC));
        ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
        builder = ImmutableList.builder();
        for (ConsumerRecord<String, String> record : records) {
            builder.add(new KafkaTextMessage(record.value()));
            log.info("We got at position: {} key:{} value: {}", record.offset(), record.key(), record.value());
            consumer.commitSync();
        }
    }
    return builder.build();
}

Upvotes: 1

Views: 3514

Answers (1)

Sa&#239;d Bouras
Sa&#239;d Bouras

Reputation: 296

Try adding auto.offset.reset=earliest in your consumer properties. The default value is set to latest. I'm suggesting this because I see that your group.id is set to test, value that you may have already use in previous tests.

Upvotes: 4

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