import os
import fcntl
import time

pid = os.getpid()

i = 10
while i > 0:
    f = open('.locktest.lck')
    print '%s %d about to lock' %  (time.time(), pid)
    rv = fcntl.lockf(f, fcntl.LOCK_EX)
    print '%s %d locked!' % (time.time(), pid)
    time.sleep(0.3)
    rv = fcntl.lockf(f, fcntl.LOCK_UN)
    print '%s %d unlocked'  % (time.time(), os.getpid())
    time.sleep(0.1)
    i = i - 1