Not 100% sure on everything you're looking for or how you're expecting things to work. But maybe this little example will at least get you going:

#!perl -w
use strict;
use warnings;
use feature 'say';
use AnyEvent::Util;

my $spawn_complete = AnyEvent->condvar;

sub spawn
{
        my $name = shift;
        my $sleep = rand 10;
        $spawn_complete->begin;
        fork_call {
                say "$name($$) about to sleep for $sleep";
                sleep $sleep;
        } sub {
                say "$name Awake!";
                $spawn_complete->end;
        };
}

# Run 5 long processes in the background
spawn $_ for qw(abc def ghi jkl mno);

# Wait for all background tasks to finish
$spawn_complete->recv;
say "All done";
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