What is asyncio.gather vs asyncio.wait?

Question

Accepted Answer

**gather** returns results in order. **wait** returns (done, pending) sets.

```python
import asyncio

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

async def main():
    # gather — returns list of results
    results = await asyncio.gather(
        slow_task(3),
        slow_task(1),
        slow_task(2)
    )
    print(results)  # [3, 1, 2] — order preserved

# wait — returns done/pending sets
    tasks = [
        asyncio.create_task(slow_task(3)),
        asyncio.create_task(slow_task(1)),
        asyncio.create_task(slow_task(2)),
    ]

# FIRST_COMPLETED
    done, pending = await asyncio.wait(
        tasks,
        return_when=asyncio.FIRST_COMPLETED
    )
    print(f"Done: {[t.result() for t in done]}")
    print(f"Pending: {len(pending)}")

# ALL_COMPLETED
    done, _ = await asyncio.wait(
        pending,
        return_when=asyncio.ALL_COMPLETED
    )

asyncio.run(main())
```

**When to use:**
- `gather`: simple collection of results.
- `wait`: partial results, timeouts, FIRST_COMPLETED.

Python: What is asyncio.gather vs asyncio.wait?