If you can't upgrade to a recent version of threads (why?), then you can achieve something similar with a shared variable (or hash as shown here if you will have multiple threads):

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


my %running :shared;

my $thread1 = threads::async  {
    {
        lock %running;
        $running{ threads->tid } = 1;
    }
    my $sleep = int(rand() * 5);

    printf "thread: %d sleeping for %d seconds\n", threads->tid, $slee
+p;
    sleep($sleep);
    printf "thread: %d Awakes\n", threads->tid;

    lock %running;
    delete $running{ threads->tid };
    printf "thread: %d about to return\n", threads->tid;
    return($sleep);
};

print "Main sleeping for 2\n";
sleep(3);
print "Main awakes\n";

if( exists $running{ $thread1->tid } ) {
    print 'email("alert")' . "\n";
} else {
   print "Thread finished in time, no problem\n";
}

print "Thread eventually returned ".$thread1->join()."\n";
print "Exit\n";

__END__
C:\test>junk
Main sleeping for 2
thread: 1 sleeping for 2 seconds
thread: 1 Awakes
thread: 1 about to return
Main awakes
Thread finished in time, no problem
Thread eventually returned 2
Exit

C:\test>junk
Main sleeping for 2
thread: 1 sleeping for 0 seconds
thread: 1 Awakes
thread: 1 about to return
Main awakes
Thread finished in time, no problem
Thread eventually returned 0
Exit

C:\test>junk
Main sleeping for 2
thread: 1 sleeping for 3 seconds
Main awakes
thread: 1 Awakes
email("alert")
thread: 1 about to return
Thread eventually returned 3
Exit
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