Hello All,
I am confused with the flock function and its usage. I have jobs which are
stored in a database, these jobs are run by a series of job_runners scripts
but sometimes the job_runners stop ( server or php crash-down). So i put a
job_controller in crontab to check regularly if the runners run. But after
a while I have a bunch of job_controller running, so to avoid that I tried
to use flock.
I try to put this in the job_controller:
$wouldblock=1;
$f=fopen("controller.lock", "r");
flock($f, LOCK_EX+LOCK_NB, $wouldblock) or die("Error! cant lock!");
hoping that as long as the first job_controller run or don't close the file
handle, a second job_controller won't be able to lock the
controller.lockfile and die, but it didn't work.
I also try this:
$wouldblock=1;
$f=fopen("controller.php", "r");
flock($f, LOCK_EX+LOCK_NB, $wouldblock) or die("Error! cant lock!");
hoping the first job_controller will lock it-self, but it didn't work.
I also thought of writing in the lock file the PID of the first
job_controller and then compare it and if it doesn't match then die, but my
main concern is , if the server crash down the "surviving" lock file will
prevent any job_controller to start.
So how could prevent multiple instance of the same script? Is flock the best
way?
Thanks in advance for your time and help
cheers
yvan
