Networking & Delivery
Message Queue
A buffer that passes tasks between parts of a system asynchronously, so slow work happens in the background instead of blocking a request.
A message queue lets one part of your system hand work to another without waiting for it to finish. A web request drops a job on the queue, returns immediately, and a separate worker picks it up and does the slow thing later. Sending email, processing uploads, generating reports, all the work that shouldn't make a user sit and wait, belongs on a queue.
The queue also smooths spikes and adds resilience. If a thousand jobs arrive at once, they line up and get processed at a sustainable rate rather than crushing your workers. If a worker dies mid-job, the message goes back on the queue for another to retry. RabbitMQ and Redis-backed queues are common, and cloud platforms offer managed options.
The pattern reshapes how you build: anything that can happen after the response should. It's the difference between a checkout that feels instant and one that hangs while it talks to a payment provider, a warehouse, and an email service in sequence.