Question

I’m creating a web app where users can specify a time and date to run 2 scheduled tasks (one at the start date and one at the end date). As these are only run once each I didn’t know if a cron job would be appropriate.

The other option I thought of would be to save all of the task times to a DB and run a cron job every hour to check if $usertime == NOW(), etc. But I was worried about jobs overlapping, etc.

Thoughts?

Additional: Many users can create many tasks that run 2 scripts each.

Answer 1

I’d do it like that, save settings in a database and check when needed if the task should start.

You could run a checking/initiating cronjob every minute. Just make sure the checking code is not not too heavy (exits quickly). A database query for a couple of rows shouldn’t be a problem to execute every minute.

If the “task” is really heavy, you should consider a daemon instead of a cronjob calling php. Here is a good & easy-to-read introduction: Create daemons in PHP

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Edit: I took for granted that even if the tasks are only ran “once each”, you have multiple users which are 1:1 to the “once each”, thereby jobs for each user. If not, at (as the comments says) looks worthy of an experiment.