#! perl -slw
use strict;
use threads;
use Thread::Queue;
use Thread::Semaphore;

my $Q = new Thread::Queue;

my $boss = async {
    my %workers;
    my %sems;

    while( <STDIN> ) {
        ( local( $_ ), my $name ) = m[([a-zA-Z])\s*(\d+)?] or next;
        warn "Non-integer thread '$name'\n" and next
            if defined $name and $name =~m[\D];

        if( m[^w]i ) {
            warn "You must give a name for the worker\n" 
                and next unless defined $name;
            warn "Worker $name already exists\n"
                and next if exists $workers{ $name };
            $sems{ $name } = new Thread::Semaphore;
            $workers{ $name } = threads->create( 
                \&worker, $name, $Q, $sems{ $name } 
            );
            next;
        }

        warn "Worker $name does not exist\n" and next
            unless m[^q] or exists $workers{ $name };

        m[^k] and $sems{ $name }->up,  ## Ensure the worker can respond
            delete( $workers{ $name } )->kill( 'KILL' )->join
            and next;

        if( m[^p] ) {
            ${ $sems{ $name } }
                ? $sems{ $name }->down
                : $sems{ $name }->up;
            $workers{ $name }->kill( 'STOP' );
            next;
        }

        m[^s] and
            $sems{ $name }->up, ## Ensure a paused thread is able to respond
            $workers{ $name }->kill( 'FPE' ),
            $sems{ $name }->down ## and set it back
            and next;

        m[^q] or next;
        for( keys %workers ) {
            $sems{ $_ }->up;
            $workers{ $_ }->kill( 'KILL' )->join;
        }
        $Q->enqueue( undef ); ## Terminate main loop
        last;
    }
};

print ">$_" while defined( $_ = $Q->dequeue );
$boss->join;
exit;


sub worker {
    my( $name, $queue, $sem ) = @_;
    my $cooldown = 0;
    my $state = 0;

    $SIG{KILL} = sub {
        warn "Worker $name dying\n";
        threads->exit();
    };
    $SIG{STOP} = sub {
        printf STDERR "Worker $name is %s\n", 
             ( $state ^= 1 ) ? 'paused' : 'resumed';
        $sem->down(); $sem->up();
    };
    $SIG{FPE } = sub {
        $queue->enqueue("Worker $name has cooldown $cooldown.");
    };

    $queue->enqueue("Worker $name starting");
    my %nodes = ();
    while (1) {
        $queue->enqueue("$name step $cooldown");
        sleep 1;
        $cooldown++;
    }
}

__END__
C:\test>743398.pl
w1
>Worker 1 starting
>1 step 0
>1 step 1
p1>1 step 2

Worker 1 is paused
s1
>Worker 1 has cooldown 2.
w2
>Worker 2 starting
>2 step 0
>2 step 1
>2 step 2
p>2 step 3
2
Worker 2 is paused
s2
>Worker 2 has cooldown 3.
k1
>1 step 3
Worker 1 dying
q
>2 step 4
Worker 2 dying