function multi_thread_curl($urlArray, $optionArray, $nThreads) {

    $curlArray = array_chunk($urlArray, $nThreads, $preserve_keys = true);
    $ch = 'ch_';
    foreach($curlArray as $threads) {      
    foreach($threads as $thread=>$value) {
    ${$ch . $thread} = curl_init();
    curl_setopt_array(${$ch . $thread}, $optionArray);  
    curl_setopt(${$ch . $thread}, CURLOPT_URL, $value);  
    }
      $mh = curl_multi_init();
      foreach($threads as $thread=>$value) {
      curl_multi_add_handle($mh, ${$ch . $thread});
      }
      $active = null;
      do {
      $mrc = curl_multi_exec($mh, $active);
      } while ($mrc == CURLM_CALL_MULTI_PERFORM);
      while ($active && $mrc == CURLM_OK) {
      if (curl_multi_select($mh) != -1) {
       do {
     $mrc = curl_multi_exec($mh, $active);
      } while ($mrc == CURLM_CALL_MULTI_PERFORM);
            }
        }
        foreach($threads as $thread=>$value) {
        $results[$thread] = curl_multi_getcontent(${$ch . $thread});
        }
        curl_multi_close($mh);
            }  
    return $results;
  
}