Experiments with WP Cron

I’ve got a couple of projects coming up which are going to require scheduling tasks in WordPress either to go off and get stuff, or to check whether posts displayed are still accurate, etc. Luckily, WordPress has a pseudo-Cron implementation which I plan to use to .

Let’s take a step back first and remember what Cron is: Cron is the scheduling service for UNIX-like systems which can set tasks occur at specific times or to recur at specific intervals. So you can use Cron to tell your system to do something at 12:47 on the 14th April, 2009 or to perform a task at 12 minutes past midnight every Monday, it’s a very useful service.

WordPress is not naturally a proactive beast, so unfortunately your WP site will not spend it’s day checking the time and seeing if it’s got anything to do. This is where the pseudo come in, with the WordPress pseudo-Cron we’re relying on a constant flow of visitors to trigger WordPress into checking for scheduled tasks. The upshot of this is that we cannot rely on WordPress to precisely schedule events, but the system is good enough for most things. (We can always increase the frequency of visitors artificially by targetting the site with five minute checks by Pingdom or similar, with the added benefit that the site is now monitored for downtime.)

So let’s get into the details of how all this stuff works, shall we? Continue reading Experiments with WP Cron