Multi curl example

gistfile1.php

<?php
/**
 * Taken from https://bugs.php.net/bug.php?id=63842
 * /

$MAX_SIMULTANEOUS = 50;  // Adjust to whatever number of maximum simultaneous requests you think is appropriate.

// Fill array $reqList[] with whatever data you're using to generate your CURL requests,
// one request per array element, with consecutive indices starting at 0.
// note that requests at the END of the array will be started first.

if ($i = count($reqList)) // check that there is something to do...
{
  $handleMap = array();  // use this to associate curl handles with the data that created them
  $curlMH = curl_multi_init();

  $x = $i - $MAX_SIMULTANEOUS; if ($x<0) $x = 0;
  while ($i>$x) initRequest($reqList[--$i]);

  do
  {
    while (($mrc = curl_multi_exec($curlMH, $active)) === CURLM_CALL_MULTI_PERFORM);
    if ($mrc !== CURLM_OK) break;  // Shouldn't normally ever happen; look at the list of CURLM_ errors to see when it might.
    while ($info = curl_multi_info_read($curlMH))  // a request has completed
    {
      $ch = $info['handle'];
      $k = intval(substr((string) $ch, 13));
      if (($errno = $info['result']) === CURLE_OK) processResult($handleMap[$k][1], curl_multi_getcontent($ch));
        else ... // handle failed CURL request, (e.g. write to the error log or database, output a message, etc.)
      if ($i) initRequest($reqList[--$i]);  // start new request if one is waiting
      curl_multi_remove_handle($curlMH, $ch); curl_close($ch); unset($handleMap[$k]);  // clean up completed request
    }
    // wait for next CURL operation to complete, or sleep a short time if CURL is busy but unable to "block" using curl_multi_select
    if ($active && (curl_multi_select($curlMH) === -1)) usleep(50);
  }
  while ($active);

  if ($mrc !== CURLM_OK) ... // optinally handle CURLM_ errors (e.g. write to error log, output message, etc.)

  // clean up
  foreach ($handleMap as $ch) { curl_multi_remove_handle($curlMH, $ch[0]); curl_close($ch); }
  curl_multi_close($curlMH);
  $reqList = $curlMH = $handleMap = null;
}

function initRequest($reqData)
{
  global $curlMH, $handleMap;

  // process $reqData to get $url (the request URL), and any POST data, or other CURL options.
  // also generate $custReqData, which will be passed to processResult to identify the request
  // when it has completed (may be the same as $reqData).

  $ch = curl_init($url);
  curl_setopt($ch, ...);   // set other CURL options
  curl_setopt($ch, ...);

  curl_multi_add_handle($curlMH, $ch);
  $handleMap[intval(substr((string) $ch, 13))] = array($ch, $custReqData);
}


function processResult($custReqData, $response)
{
  // process $response (the data returned from the CURL request)
  // using $custReqData to identify which request it belongs to.
}
?>