Asyncio Tasks, Futures & asyncio.gather()

1Concept

`asyncio.create_task()` wraps a coroutine into a `Task` and schedules it on the event loop immediately. `asyncio.gather(*tasks)` runs multiple concurrent tasks in parallel, waiting for all to resolve and returning results in submission order.

2Architecture Diagram

asyncio.gather(Task A, Task B, Task C) ---> Concurrently executes all 3 ---> Returns [resA, resB, resC]

3Code Example

import asyncio

async def simulate_api(endpoint: str, latency: float) -> str:
    await asyncio.sleep(latency)
    return f"Response from {endpoint}"

async def main():
    # Schedule both calls concurrently
    res1, res2 = await asyncio.gather(
        simulate_api("/users", 0.02),
        simulate_api("/orders", 0.01)
    )
    print(res1)
    print(res2)

asyncio.run(main())

4Expected Output

Response from /users
Response from /orders

5Key Takeaways

• ✓`asyncio.gather()` preserves result ordering matching the input argument order.
• ✓Pass `return_exceptions=True` to prevent a single failure from aborting all gathered tasks.
• ✓Always maintain references to running tasks to prevent garbage collection mid-execution.