如何退出Flask应用程序中调用的python脚本？

Question

I have a flask app where I am reusing a function in a python script (poll_servers.py). I can import the function and run it but I want to put a check in place that exits the function if it's running.

Here is my code in the python script:

import os
import sys

# check if lock file exists, exit
if os.path.exists('static/poll.lock'):
    sys.exit(1)

if not os.path.exists('static/poll.lock'):
    with open('static/poll.lock', 'w'): pass

In my app.py I have:

from poll_servers import poll

@app.route('/poll_servers', methods=['GET'])
def poll_servers():

    response = json.dumps({'status':'OK'})

    poll()

    return response

I get an error on the sys.exit(1) in poll_servers.py:

File "app.py", line 109, in poll_servers
  poll()
File ".../poll_servers.py", line 262, in poll
  sys.exit(1)
File ".../venv/lib/python2.7/site.py", line 403, in __call__
  raise SystemExit(code)
SystemExit: None

Any ideas? If I run the poll_servers.py on its own the sys.exit(1) works fine.

Answer 1

Then just don't do anything or flip the order of your if statement:

import os
import sys

if not os.path.exists('static/poll.lock'):

    with open('static/poll.lock', 'w'): 

        pass

else:

    pass
    # do something