What do you do with DLT topics?

DLT (Dead Letter Topic) in Kafka is used for handling messages that could not be processed correctly by the main consumer. Typically, with DLT topics, the following is done:

• A separate error topic is configured where problematic messages are sent.
• When an error occurs during message processing in the consumer, the message is published to the DLT with additional information (e.g., error reason).
• Periodically or triggered, a separate process is run to analyze and reprocess messages from the DLT.

Example in Java using Kafka Consumer:

try {
    // process message
} catch (Exception e) {
    // send to DLT
    ProducerRecord<String, String> dltRecord = new ProducerRecord<>("my-topic.DLT", key, value);
    producer.send(dltRecord);
}

Thus, DLT helps isolate problematic messages and prevents blocking the main processing flow.