500: my $time = time();
  DB<4> n
Queue::MySQLQ::dequeue(/Users/foo/lib/Queue/MySQLQ.pm:501):
501: my $expire_time = $time + $WORKER_HEARTBEAT_FAILURE;
  DB<4> x $time
0  1238124047
  DB<5> x time()
0  1238124062
  DB<6> sleep 2

  DB<7> x time()
0  1238124062