A queue holds work items in first-in, first-out order: the item added first is the first one removed. Like a checkout line, items join at the end and leave from the front. section 12.1
An asynchronous queue lets multiple workers take available items concurrently. A bounded queue also limits how many items can wait or how much work proceeds at once. section 12.1 section 12.1.1
Queues solve two practical coordination problems:
- They distribute work among workers, such as cashiers processing customers from one checkout line. section 12.1
- They move slow operations into background tasks, allowing a web endpoint to respond before order processing finishes. section 12.1.1
- They can apply backpressure: putting into a full bounded queue waits or raises an exception, depending on the method used. section 12.1.1
Background order processing
An aiohttp endpoint places an order on an asyncio.Queue and immediately acknowledges it. Worker tasks retrieve orders, simulate slow processing, and call task_done(); limiting the queue and worker count controls load on the order system. section 12.1.1
