How do you handle a slow consumer — a client that does not read messages?

A slow consumer is a client that does not keep up with reading messages from a queue or topic, which can lead to message accumulation and issues with performance or data loss.

Several approaches are used to handle such clients:

• Queue size limitation. If the queue overflows due to slow consumption, new messages may be discarded or old ones removed according to TTL policy.
• Monitoring consumer status. Tracking delays and processing speed helps identify slow consumers and take measures.
• Using backpressure mechanisms. If the client cannot keep up, the server can slow down message sending or temporarily suspend it.
• Implementing retries and dead-letter queues. Messages that are not processed can be sent to a separate queue for later analysis.

In practice, for example in systems with RabbitMQ or Kafka, limits are set for slow consumers and monitoring is used to either scale consumers or redistribute load.