How is exec performed in PHP?

Question

PHP

Hello.
I wondered what would happen if a bash script is executed in a php script via exec (file processing)
And 2 requests for the PHP script that starts up arrive at the same time (almost simultaneously. With a difference of a couple of cycles)
Will 2 instances of the bash script start and they will both work in parallel or one cover another?

Answer 1

Two instances will start