I think you need to use:

GNU parallel is a shell tool for executing jobs in parallel using one or more computers. A job can be a single command or a small script that has to be run for each of the lines in the input. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables. A job can also be a command that reads from a pipe. GNU parallel can then split the input and pipe it into
commands in parallel.

Nice tutorial can be found:

https://davetang.org/muse/2013/11/18/using-gnu-parallel/

https://www.codeword.xyz/2015/09/02/three-ways-to-script-processes-in-parallel/

If you add an example of how you do it without GNU Parallel, then you may have more luck getting a usable answer.