Extract an Excel in background (for large files)

Hi,

I'm Kaitenz, nice to meet you.

I don't want to post a question in StackOverflow because you need a code so you can get some answer/s.
But I don't have the code and I'm using CodeIgniter so I will ask it here. 

I want to create a controller that will allow the users to upload a very large Excel file (I am using PhpSpreadsheet to read Excel files).
And since I will do data validation for each column and then write it to the database, it will take time to process.

My plan is to create a background process for this. Once done uploading the file to the server (just upload, no data validation or insertion process is happening), the user can now leave the page and let the PHP process it in background. But how can I achieve this? I tried searching it around the web but any search terms I've used, doesn't answer my question. 


Still learning to develop using PHP and CodeIgniter. So please bear with me. Thanks.

 Kaitenz