Is there a way to run a function within my module asynchronously as a background process?

[hgotfred]

So I have a addon module...

I have a method called "migration" in the client controller of the module and I have a separate function within the "migration" controller method which I want to execute asynchronously, as to immediately return to the client from the "migration" method and do the work afterwards.

How do I do this in whmcs? I tried using exec() to run the function as a php script but didn't get it to work. Does this have something to do with exec() running the script outside the WHMCS system context?

Are there any fool proof methods for this in WHMCS?

Thank you