PHP Asynchronous execution related issues

PHP Asynchronous execution issues
When PHP executes the Exec () method, it waits for the Exec method to execute completely before continuing with the rest of the code
and exec () executes for a long time, so the page is always waiting,
will not refresh until exec finishes executing.
So is there a way to make exec perform in the background while the page doesn't have to wait for exec to finish to refresh?

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------Solution--------------------
Try to add a & after the command being executed
But not all commands can be executed in the background.
------Solution--------------------
This does not seem to be possible, you can get an event queue on the server side, when server 2 received 3 of the request to add an event, on server 2 write a processing event program.

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