PHP怎么实现curl批量请求

<?php
$ch = array();
$res = array();
$conn = array();
$urls = array(
  'baidu' => "http://www.baidu.com/",
  'cheyun' => "http://auto.jrj.com.cn/",
  'w3c' => "http://www.w3cschool.cc/",
);
// 创建批处理cURL句柄
$mh = curl_multi_init();
foreach ($urls as $i => $url) {
  // 创建一对cURL资源
  $conn[$i] = curl_init();
  // 设置URL和相应的选项
  curl_setopt($conn[$i], CURLOPT_URL, $url);
  curl_setopt($conn[$i], CURLOPT_HEADER, 0);
  curl_setopt($conn[$i], CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($conn[$i], CURLOPT_TIMEOUT, 10);
  //302跳转
  curl_setopt($conn[$i], CURLOPT_FOLLOWLOCATION, 1);
  // 增加句柄
  curl_multi_add_handle($mh, $conn[$i]);
}
$active = null;
//防卡死写法：执行批处理句柄
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 ($urls as $i => $url) {
  //获取当前解析的cURL的相关传输信息
  $info = curl_multi_info_read($mh);
  //获取请求头信息
  $heards = curl_getinfo($conn[$i]);
  var_dump($heards);
  //获取输出的文本流
  $res[$i] = curl_multi_getcontent($conn[$i]);
  // 移除curl批处理句柄资源中的某个句柄资源
  curl_multi_remove_handle($mh, $conn[$i]);
  //关闭cURL会话
  curl_close($conn[$i]);
}
//关闭全部句柄
curl_multi_close($mh);
//var_dump($res);