Just a simple idea for you...can you put a shared variable in each thread called $im_alive, and set it to 1 when the thread is launched, and have the thread set it to 0 just before it exits. Of course that requires you to track each thread (and it's associated shared variable) in a hash if you have more than one thread going. There also may be timing problems in checking the shared:var, you may need to allow time for the thread to initiate before checking it. I avoided this by setting the shared var to 1 outside of the thread.

#!/usr/bin/perl
use warnings;
use strict;
use threads;
use threads::shared;

my $im_alive : shared = 1;

my $thread = async {sleep 10;
                    print "Ok\n";
                    $im_alive = 0;
                    };
my $i = 0;
while (1) {
   $i++;
   print "$i - $thread\n";
    print "im_alive->$im_alive\n";
    if ($im_alive == 0) {last};
         sleep 1;
  };

print "im_alive->$im_alive\n";
print "hit enter to exit\n";
<>;
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