What is a wait() function?

In the context of asynchronous programming in Python using the asyncio module, the asyncio.wait() function is used to wait for multiple coroutines to complete.

Main aspects:

• Returns two tuples: (done, pending).
  • done: A set of coroutines that have finished (returned a result, raised an exception, or were canceled).
  • pending: A set of coroutines that have not yet finished.
• Accepts an iterable of coroutines (or objects awaiting completion, such as tasks).
• Allows controlling the completion conditions:
  • return_when: Determines when wait should return. It can be asyncio.FIRST_COMPLETED, asyncio.FIRST_EXCEPTION, asyncio.ALL_COMPLETED (default value).
  • timeout: Maximum waiting time in seconds. If some tasks do not finish within this time, they are placed in the pending set.
• Unlike asyncio.gather(), which returns results as a list after all coroutines complete, asyncio.wait() returns sets of completed and pending coroutines and does not automatically collect results.

Example usage:

import asyncio

async def coro1():
    await asyncio.sleep(1)
    print("coro1 finished")
    return "Result 1"

async def coro2():
    await asyncio.sleep(2)
    print("coro2 finished")
    # raise ValueError("Something went wrong")
    return "Result 2"

async def main():
    task1 = asyncio.create_task(coro1())
    task2 = asyncio.create_task(coro2())

    # Wait for all tasks to complete
    done, pending = await asyncio.wait([task1, task2], return_when=asyncio.ALL_COMPLETED)

    print("Wait finished")

    for task in done:
        try:
            result = task.result()
            print(f"Task result: {result}")
        except Exception as e:
            print(f"Task raised exception: {e}")

asyncio.run(main())