When to call KafkaProducer close method? - apache-kafka

Question

As Kafka document said that,
The producer is thread safe and sharing a single producer instance
across threads will generally be faster than having multiple
instances.
So I have following code and want to only have one instance of KafkaProducer for each send request. But when is the best place in the code to call close method on it? As I can't call close method in the send method. How should I write the code to handle?
public class Producer {
private final KafkaProducer<Integer, String> producer;
public Producer(String topic, Boolean isAsync) {
Properties props = new Properties();
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KafkaProperties.KAFKA_SERVER_URL + ":" + KafkaProperties.KAFKA_SERVER_PORT);
props.put(ProducerConfig.CLIENT_ID_CONFIG, "DemoProducer");
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, IntegerSerializer.class.getName());
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
producer = new KafkaProducer<>(props);
}
public void send(String message) {
producer.send(new ProducerRecord<>(topic, messageNo, messageStr);
}
}

Answer 1

You can create the producer first and pass(inject) it to your web resource or resources.
Then you can use a shutdown hook to close the producer with its reference.
Even better if you can use life cycle stop hooks in your framework.
Example in dropwizard:
https://www.dropwizard.io/en/latest/manual/core.html?highlight=managed#managed-objects

Answer 2

Kafka producer implements the AutoClosable interface. So you can declare it within the try-with-resources block, and it should take care of releasing the resources when your code goes outside the scope of the block.

Answer 3

Do you ever need to change producer parameters at runtime? For example when changing the broker urls or during tests?
If you need it and you have a singletone producer, make sure to provide a hook to close and recreate the producer with new parameters.