use strict;
use warnings;
use POSIX ':sys_wait_h';

my @subs_to_run = (
    \&sub1,
    \&sub2,
    \&sub3,
    \&sub4,
    \&sub5,
);
foreach my $sub (@subs_to_run) {
    my $is_parent = fork;  # try to fork
    next if $is_parent;    # both child and fork failure will be false

    $sub->();  # we're in the child or fork failed, run the sub

    exit if defined $is_parent;  # exit only if actually forked
}

1 while waitpid(-1, WNOHANG) > 0;  # wait for all children