I need to have several functions running concurrently and infinitely. I plan to use asyncio for this, and, if possible, I want to avoid using event loop directly.
I tried this code:
import asyncio
import os
class Program:
def __init__(self):
self.files = os.listdir('data')
self.last_file = ''
self.history = []
async def wait_new_file(self):
await self._wait_new_file()
def _wait_new_file(self):
while True:
checked_files = set(os.listdir('data'))
if new_file := checked_files.difference(set(self.files)):
print(f'{new_file = }')
self.last_file = list(new_file)[0]
self.files.append(list(new_file)[0])
self.history.append(f'>>>{self.files[-1]}')
print(f'{self.files = }')
if deleted_file := set(self.files).difference(checked_files):
print(f'{deleted_file = }')
self.files.remove(list(deleted_file)[0])
print(f'{self.files = }')
if os.path.exists('stop'):
print(self.history)
return
async def check_difference(self):
await self._check_difference()
def _check_difference(self):
flip = True
while True:
if flip and os.path.exists('flip'):
flip = False
print('on')
if not flip and not os.path.exists('flip'):
flip = True
print('off')
if os.path.exists('stop'):
return
async def main(self):
async with asyncio.TaskGroup() as tg:
task_check_difference = tg.create_task(self.check_difference())
task_monitor_files = tg.create_task(self.wait_new_file())
program = Program()
asyncio.run(program.main())
But with this, task_monitor_files is not doing any job, please tell what is wrong there?
2
Ur problem is the way ur using asyncio and await’s
In _wait_new_file and _check_difference methods, ur using while True loops, which is blocking some code.
When you call await self._wait_new_file() or await self._check_difference(), the execution will be stuck in these loop’s and never return.
To fix this, you should make those methods async by using asyncio.sleep() instead of busy-waiting.
Here’s an better version of your code:
import asyncio
import os
class Program:
def __init__(self):
self.files = os.listdir('data')
self.last_file = ''
self.history = []
async def wait_new_file(self):
while True:
... # ur code
await asyncio.sleep(1) # wait for 1 second before checking again
async def check_difference(self):
flip = True
while True:
... # ur code
await asyncio.sleep(1) # wait for 1 second before checking again
async def main(self):
async with asyncio.TaskGroup() as tg:
task_check_difference = tg.create_task(self.check_difference())
task_monitor_files = tg.create_task(self.wait_new_file())
program = Program()
asyncio.run(program.main())
Hope this will help you.