What is asyncio.wait and when to use it over gather?

Question

Accepted Answer

**asyncio.wait** provides **finer control** over task execution than gather.

```python
import asyncio

async def slow_task(n):
    await asyncio.sleep(n)
    return n

async def main():
    tasks = [
        asyncio.create_task(slow_task(1)),
        asyncio.create_task(slow_task(3)),
        asyncio.create_task(slow_task(2)),
    ]

# FIRST_COMPLETED — return as soon as one finishes
    done, pending = await asyncio.wait(
        tasks, return_when=asyncio.FIRST_COMPLETED
    )
    for task in done:
        print(f"Done: {task.result()}")

# FIRST_EXCEPTION — return on first exception
    # ALL_COMPLETED — wait for all

asyncio.run(main())
```

**Return modes:**
- `FIRST_COMPLETED` — any task finishes.
- `FIRST_EXCEPTION` — first exception raised.
- `ALL_COMPLETED` — all tasks done.

**vs gather:**
- `wait` returns (done, pending) sets.
- `gather` returns results list.
- Use `wait` when you need partial results.

Python: What is asyncio.wait and when to use it over gather?