python async context trace

async_context.py

import asyncio
from contextvars import ContextVar

ctx = ContextVar[int]("myctx")


async def bar():
    await asyncio.sleep(1)
    print(ctx.get(), end=" ")


async def main():
    promises = []
    for i in range(10):
        promises.append(wrapper(i, bar))
    await asyncio.gather(*promises)


async def wrapper(x, f):
    ctx.set(x)
    await f()


asyncio.run(main())

# Output: 0 1 2 3 4 5 6 7 8 9