Python fcntl does not lock as expected[file lock]http://stackoverflow.com/questions/9907616/python-fcntl-does-not-lock-as-expected

filelock.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import fcntl
import sys
import time


def lockFile(f):
    try:
        fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        return False
    return True

fp = open("/tmp/tmp.txt", 'w')
a = lockFile(fp)
if not a:
    sys.exit(0)
else:
    print("Locked the file...")

while 1:
    time.sleep(10)