asyncio queues in Python

A producer and consumer sharing an async queue.

import asyncio


async def producer(queue):
    for job in ["resize", "encode", "upload"]:
        await queue.put(job)
    await queue.put(None)  # sentinel


async def worker(queue, done):
    while (job := await queue.get()) is not None:
        done.append(job)


async def main():
    queue, done = asyncio.Queue(), []
    await asyncio.gather(producer(queue), worker(queue, done))
    return done

finished = asyncio.run(main())

How it works

1. The producer puts jobs, then a None sentinel.
2. The worker loops with := until the sentinel.
3. gather runs both coroutines together.

Keywords and builtins used here

• async
• await
• def
• for
• main
• producer
• return
• while
• worker

The run, in numbers

Lines

20

Characters to type

394

Tokens

118

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 64 seconds.

Type this snippet

Step 4 of 4 in Async, step 27 of 53 in Pythonic Python.

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