$max = 800000;
$workers = 20;
$pids = array();
for($i = 0; $i < $workers; $i++){
  $pids[$i] = pcntl_fork();
  switch ($pids[$i]) {
    case -1:
      echo "fork error : {$i} \r\n";
      exit;
    case 0:
      $param = array(
        'lastid' => $max / $workers * $i,
        'maxid' => $max / $workers * ($i+1),
      );
      $this->executeWorker($input, $output, $param);
      exit;
    default:
      break;
  }
}
foreach ($pids as $i => $pid) {
  if($pid) {
    pcntl_waitpid($pid, $status);
  }
}