What do you think is the point of this code?:

$thr->suspend();
$thr->yield();
[download]

Given that it is proceed by: $thr->join(); which means that the thread no longer exists by the time the above two lines are executed. In addition, the ->yield() method of the threads module isn't exported by default, and you do not import it.

Your code is exactly equivalent to:

#!/usr/bin/perl
use strict;
use warnings;

$|=1;

my $TERM = 0;

$SIG{'INT'} = $SIG{'TERM'} = sub { $TERM = 1; };
print "To terminate program, hit ctrl-^C\n";

print( join(' ', ()) );
sleep (1) until ($TERM);
[download]

In other words it does exactly nothing useful and is in no way an answer to the OPs question.