lock_pid.py

if __name__ == '__main__':
    pid_file = cur_file_dir() + '/logstat.pid'
    fp = open(pid_file, 'w')
    try:
        fcntl.lockf(fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        # another instance is running
        sys.exit(0)