PHP - 一起使用Cron Jobs和GD

Question

I have a customer based website which requires them to upload an image, and on doing so my script will save about 25-30 variations of the image onto the server using the GD library. Because of the amount of images there is currently a very long waiting time for the customer to continue on the site waiting until all images have been created and saved. Until then they cannot proceed so we get a high level of customers leaving the site.

Is it possible after upload to instead store the image url in a database table record, then have a php script which creates the 25-30 images pull each record in the database and run every 5 minutes of the day using cronjob. This way it allows the customer to continue through the website and have the images automatically created 'in the background'

Will all this going on in the background cause any issues for the speed of my site? Will it slowdown the site for people browsing especially if 10-100's of customers are using it at the same time?

Answer 1

Having a PHP script process the images would cause no more lag in a cron job than it would when the customer uploads the image and waits for the processing to complete in realtime. So in short, no there's no additional impact of this approach.

The catch is, you need to make sure your cron job is self-aware and does not create overlaps. For example if the cron runs and takes more than 5 minutes to complete its current task, what happens when a second cron spins up and begins processing another image (or the same one if you didn't implement the queue properly)? Well now you have two crons running, fighting for resources. Which means the second one will likely take over 5 minutes as well. Eventually you get to the point with 3, 4, etc crons all running at once. So make sure your crons are only "booting up" if there's not one running already.

All this being said, you'd probably be best off having another server handle the image processing depending on the size of your client's site and how heavy their traffic is. You could have a cloud server in a cluster with your production site server which can connect via local network to access an image, process it, and return the 25-30 copies to the server in the appropriate location. This way your processing queue occupies 0 resources of the public facing web server and will have no impact on speed of the site itself.