Daniel Arbuckle's Mastering Python

Queue types

asyncio provides a couple of variant Queue types that return their stored values in different orders.

Instances of PriorityQueue give back the smallest object they contain according to a less than comparison when we call get or get_nowait. So, if our priority queue contains 34, 2, 5, and 97, calling its get coroutine would return 2. The next time, it would return 5, then 34, and then 97.

A LifoQueue method, on the other hand, always gives back the most recently added object. It is, in other words, a stack data structure. asyncio also provides a joinable Queue class, which adds an extra join coroutine and a method called task_done. With a little bit of extra work, using a joinable queue allows coroutines to pause and wait until ...