use Carp;

sub sub1 { sub3(); sub2(); }
# want the backtrace down to sub2 or sub3
sub sub2 { die "code failure"; }
sub sub3 { die "runtime error" if rand() < 0.25 }

sub main_sub {
  eval {
    #$dbh->begin_work;

    # various things, not all db-related
    sub1();

    # more things

    #$dbh->commit;
  };

  if ($@) {
    #$dbh->rollback;
    print STDERR $@;
    confess "the transaction failed";
  };
}

main_sub();