script.py

import asyncio
import aiofiles

async def reader():
    async with aiofiles.open('file.txt', mode='r') as name_file:
        while True:
            yield await name_file.readline()

async def fetcher(reader_gen, i):
    print('Opening {}'.format(i))
    while(True):
        name = await reader_gen.__anext__()
        if name.strip():
            # line has some value
            print('Got name "{}" for {}'.format(name.strip(), i))
        elif name:
            # implies it contains only '\n', ie empty line
            print('Got an empty line for {}'.format(i))
            pass
        else:
            # reaching here is EOF
            print('No more names. Closing {}'.format(i))
            break
        # await asyncio.sleep(0)
        # uncommenting above line gives the intended output, implying that aiofiles fails to async the file io call, right?

looper = asyncio.get_event_loop()
tasks = []
reader_gen = reader()
for i in range(5):
    tasks.append(asyncio.ensure_future(fetcher(reader_gen, i)))
looper.run_until_complete(asyncio.wait(tasks))
reader_gen.aclose()


# # file.txt
# name1
# name2
# name3
#
# name4
# name5
# name6


# # output
# Opening 0
# Opening 1
# Opening 2
# Opening 3
# Opening 4
# Got name "name1" for 0
# Got name "name2" for 0
# Got name "name3" for 0
# Got an empty line for 0
# Got name "name4" for 0
# Got name "name5" for 0
# Got name "name6" for 0
# No more names. Closing 0
# No more names. Closing 1
# No more names. Closing 2
# No more names. Closing 3
# No more names. Closing 4


# # expected output
# Opening 0
# Opening 1
# Opening 2
# Opening 3
# Opening 4
# Got name "name1" for 0
# Got name "name2" for 1
# Got name "name3" for 2
# Got an empty line for 3
# Got name "name4" for 4
# Got name "name5" for 0
# Got name "name6" for 1
# No more names. Closing 0
# No more names. Closing 1
# No more names. Closing 2
# No more names. Closing 3
# No more names. Closing 4