Your problem is that you are trying to use perl as if it was C.

This:

sub protocol($srv) {
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Does not declare a function that takes a single argument called $srv.

You need to learn how to use perl before you start playing with threads; otherwise you will just blame threading for your own mistakes.

You should start by reading perlsub and writing some simple (non-threaded!) programs that use subroutines and pass arguments.

Once you understand how to pass arguments and what "prototypes" are, you may be ready to progress to the next level.