Preventing Cron Job Collision

Prevents jobs to collide if they take longer to run than the frequency itself

1. $fp = fopen(‘/tmp/lock.txt’, ‘r+’);
3. if(!flock($fp, LOCK_EX | LOCK_NB)) {
4.    echo ‘Unable to obtain lock’;
5.    exit(-1);
6. }
8. /* … */
10. fclose($fp);