use threads::shared;

my $semSO :shared;
sub tprint  { lock $sem; print  @_; }
sub tprintf { lock $sem; printf @_; }

my $semSE :shared;
sub twarn{  lock $semSE; print  STDERR @_; }
sub twarnf{ lock $semSE; printf STDERR @_; }

...
tprint( $some, "Stuff" );
...

else twarnf( "%u %s\n", $this, $that );