Analysis of methods for implementing multi-threading using foreach combined with curl in PHP

The example in this article describes the method of using foreach combined with curl to achieve multi-threading in PHP. Share it with everyone for your reference, the details are as follows:

Multi-threading is not supported by PHP, but we can use foreach to pseudo-multi-thread, but this pseudo-multi-threading is not necessarily faster than single-threading. Specifically, Let’s look at an example.

When using the foreach statement to loop through image URLs and save all images locally through CURL, a problem arises that only one can be collected. Now we will combine foreach and CURL to make multiple URL requests. Summary below.

Method 1: Loop request

$sr=array(url_1,url_2,url_3);
foreach ($sr as $k=>$v) {
 $curlPost=$v.'?f=传入参数';
 $ch = curl_init($curlPost) ;
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, true) ; // 获取数据返回
 curl_setopt($ch, CURLOPT_BINARYTRANSFER, true) ; // 在启用 CURLOPT_RETURNTRANSFER 时候将获取数据返回
 $data = curl_exec($ch) ;
 echo $k.&#39;##:&#39;.$data.&#39;<br>&#39;;
}
curl_close($ch);

What needs special attention in the above code is that curl_close must be placed outside the end of the foreach loop. If it is placed inside, the problem I mentioned above will appear. Multiple IMGURLs can only collect one URL.

Method 2: Multi-threaded loop

<?php
multi_threads_request($nodes){
  $mh = curl_multi_init();
  $curl_array = array();
  foreach($nodes as $i => $url)
  {
   $curl_array[$i] = curl_init($url);
   curl_setopt($curl_array[$i], CURLOPT_RETURNTRANSFER, true);
   curl_multi_add_handle($mh, $curl_array[$i]);
  }
  $running = NULL;
  do {
   usleep(10000);
   curl_multi_exec($mh,$running);
  } while($running > 0);
  $res = array();
  foreach($nodes as $i => $url)
  {
   $res[$url] = curl_multi_getcontent($curl_array[$i]);
  }
  foreach($nodes as $i => $url){
   curl_multi_remove_handle($mh, $curl_array[$i]);
  }
  curl_multi_close($mh);
  return $res;
}
print_r(multi_threads_request(array(
 &#39;http://www.php.cn&#39;,
 &#39;http://tools.php.cn&#39;,
));

Here we mainly use curl_multi_init() to implement multiple url requests, but because PHP itself does not support multi-threading , so the speed of pseudo-multithreading is not necessarily faster than that of single-threading.

I hope this article will be helpful to everyone in PHP programming.

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