foo.p6

react {
    my $batch-size = $*KERNEL.cpu-cores;
    my @queue = eager 0..10; # Populate your jobs data here

    sub do-one {
        with @queue.shift -> $el {
            my $proc = Proc::Async.new(...);
            whenever $proc.out -> $output {
                ...processing $output...
            }
            whenever $proc.start -> $exit {
                ...some post-processing...;
                do-one();
            } 
        }
    }

    do-one for ^$batch-size;
}