Please help: Prevent Multiple Instances

Hi All,

How can I prevent a script from running when a previous instance of
the script had already been triggered and the script is running in the
background already?
So, even when a script is startet several times (eg. by several
website visitors) I want only one script-instance running on the
server. Subsequent instances should be exited (or prevented) right
away to keep the server load as low as possible.

However, when no instance of the script is currently running (eg.
after a server shut-down), triggering the script should make it run -
but again: only one instance should be running at all times. Further
script calls, as said above, should then not be allowed.

Any ideas?
Thanks a ton if somebady can help me.
Jerry

Hello,

On 06/07/2004 05:09 AM, Jerry wrote:
> How can I prevent a script from running when a previous instance of
> the script had already been triggered and the script is running in the
> background already?
> So, even when a script is startet several times (eg. by several
> website visitors) I want only one script-instance running on the
> server. Subsequent instances should be exited (or prevented) right
> away to keep the server load as low as possible.
>
> However, when no instance of the script is currently running (eg.
> after a server shut-down), triggering the script should make it run -
> but again: only one instance should be running at all times. Further
> script calls, as said above, should then not be allowed.

I use flock() to obtain a lock in a specified file to be associated with
the task. The first script to obtain the lock will prevent others to
grab it.

--

Regards,
Manuel Lemos

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