What is a message queue and what are common patterns used for?

What is a message queue and what are common patterns used for?

• A. A message queue stores logs locally.
• B. A message queue is used only for real-time chat.
• C. A message queue automatically scales databases.
• D. A message queue decouples producers and consumers; pub/sub broadcasts messages to multiple subscribers; worker queues offload background tasks to workers.

Answer: (D)

A message queue is a system that stores messages sent by producers until a consumer is ready to process them, enabling asynchronous, decoupled communication and buffering between parts of a system. This decoupling lets producers push messages and move on without waiting for processing, while consumers pull or receive messages at their own pace, which helps handle bursts of traffic and failures gracefully. The common patterns you’ll see are: decoupling producers and consumers, where the queue acts as a buffer between who sends data and who processes it; publish/subscribe, where a message is broadcast to multiple interested subscribers so several components can react to the same event; and worker queues, where tasks are placed in the queue and a pool of workers processes them in the background, improving throughput for long-running or resource-intensive work. These patterns together support reliability, scalability, and responsive systems.