PHP Background Process

Question

I have a process users must go through on my site which can take quite a bit of time (upwards of an hour in certain cases).

I'd like to be able to have the user start the process, then be told that it is running in the background and they can leave the page and will be emailed when the process is complete. This would help avoid cases when the user gets impatient and closes the window before the process has finished.

An example of how it would ideally look is how Mailchimp handles importing contacts. You upload a CSV file of your contacts, and they then say that the contacts are currently uploading, but it can take a while so feel free to leave the page.

What would be the best way to accomplish this? I looked into Gearman, however it seems like that tool is more useful for scaling large amounts of tasks to happen quickly, not running processes in the background.

Thanks for your help.

Answer 1

Even it doesn't seem to be what you'd use at the first look, I think I would use Gearman, for that :

• You can push tasks to it when the user does his action
• It'll deal with both :
  • balancing tasks to several servers, if you have more than one
  • queuing, so no more than X tasks are executed in parallel.
• No need to re-invent the wheel ;-)

Answer 2

You might want to take a look at creating a daemon. I'd suggestion writing the daemon in a language other than PHP (node.js maybe?), but if you already have a large(ish) code base in PHP this mightn't be desirable. Try taking a look at How to design a daemon with a MySQL DB connection .

I've been working on a library call LooPHP in PHP to allow event driven programming for PHP (often desirable for daemons). The library allows for timed events, multi-threaded listeners (when you want one event queue to be feed from >1 type of source).

If you could give us some more information on what exactly this background process does, it might be helpful.

Answer 3

Write out a file using the user's ID as the filename. Spawn a new process to perform whatever it is you want it to do (if what you want is to have it execute some more PHP, then you can just call PHP with the script you want to run). When that process is done, have it delete that file. If the user visits the page again, have the script check for existence of the file (since the filename is predictable based on user ID). If it exists, then you're still processing, so tell them to continue waiting. Maybe have some upper bound to wait, where if they come back and the file exists, but it's been, say, 5 hours, delete the file and let them try again.