推薦：《PHP視頻教程》

先來看下同步的代碼以及請求時間。

$start_time=date("h:i:sa"); for ($i=0; $i <100 ; $i++) {  	$urls[]="http://www.downxia.com/downinfo/2315".$i.".html"; 	GetTitle(geturl("http://www.downxia.com/downinfo/2315".$i.".html")); } function geturl($url){                 $ch = curl_init();         curl_setopt($ch, CURLOPT_URL, $url);         curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);                  $output = curl_exec($ch);         curl_close($ch);          return $output; } function GetTitle($output){  	preg_match('/<title>.*</title>/i',$output,$matches); 	var_dump($matches[0]); } $end_time=date("h:i:sa"); echo '開始時間是：'.$start_time; echo '結(jié)束時間是：'.$end_time;

最下面可以看到時間花了27秒。

接下來看下php curl 異步并發(fā)請求http的代碼以及花費(fèi)時間。

$start_time=date("h:i:sa");  $urls=[]; for ($i=0; $i <100 ; $i++) {  	$urls[]="http://www.downxia.com/downinfo/2315".$i.".html"; } var_dump($urls); // GetTitle('klasjdkla<title>313asds12</title>');  rolling_curl($urls,'GetTitle');  function GetTitle($output){  	preg_match('/<title>.*</title>/i',$output,$matches); 	var_dump($matches[0]); } $end_time=date("h:i:sa");  echo '開始時間是：'.$start_time; echo '結(jié)束時間是：'.$end_time;  function rolling_curl($urls, $callback, $custom_options = null) {//多個url訪問      // make sure the rolling window isn't greater than the # of urls     $rolling_window = 5;     $rolling_window = (sizeof($urls) < $rolling_window) ? sizeof($urls) : $rolling_window;      $master   = curl_multi_init();     $curl_arr = array();      // add additional curl options here     $std_options = array(         CURLOPT_RETURNTRANSFER => true,         CURLOPT_FOLLOWLOCATION => true,         CURLOPT_MAXREDIRS      => 5         );     $options = ($custom_options) ? ($std_options + $custom_options) : $std_options;      // start the first batch of requests     for ($i = 0; $i < $rolling_window; $i++) {         $ch                   = curl_init();         $options[CURLOPT_URL] = $urls[$i];         curl_setopt_array($ch, $options);         curl_multi_add_handle($master, $ch);     }      do {         while (($execrun = curl_multi_exec($master, $running)) == CURLM_CALL_MULTI_PERFORM);         if ($execrun != CURLM_OK) {             break;         }          // a request was just completed -- find out which one         while ($done = curl_multi_info_read($master)) {             $info = curl_getinfo($done['handle']);             if ($info['http_code'] == 200) {                 $output = curl_multi_getcontent($done['handle']);                  // request successful.  process output using the callback function.                 $callback($output);                  // start a new request (it's important to do this before removing the old one)                 $ch                   = curl_init();                 $options[CURLOPT_URL] = $urls[$i++]; // increment i                 curl_setopt_array($ch, $options);                 curl_multi_add_handle($master, $ch);                  // remove the curl handle that just completed                 curl_multi_remove_handle($master, $done['handle']);             } else {                 // request failed.  add error handling.             }         }     } while ($running);      curl_multi_close($master);     return true; }

才花了3秒？實際上我感覺應(yīng)該是花了5秒，因為啟動比同步要慢，開始的時候卡了2秒。

http請求效率，毋庸置疑是異步遠(yuǎn)遠(yuǎn)高于同步。

核心請求代碼如下：（這是老外寫的，有點小問題，最后的提示undefined offset）

function rolling_curl($urls, $callback, $custom_options = null) {//多個url訪問      // make sure the rolling window isn't greater than the # of urls     $rolling_window = 5;     $rolling_window = (sizeof($urls) < $rolling_window) ? sizeof($urls) : $rolling_window;      $master   = curl_multi_init();     $curl_arr = array();      // add additional curl options here     $std_options = array(         CURLOPT_RETURNTRANSFER => true,         CURLOPT_FOLLOWLOCATION => true,         CURLOPT_MAXREDIRS      => 5         );     $options = ($custom_options) ? ($std_options + $custom_options) : $std_options;      // start the first batch of requests     for ($i = 0; $i < $rolling_window; $i++) {         $ch                   = curl_init();         $options[CURLOPT_URL] = $urls[$i];         curl_setopt_array($ch, $options);         curl_multi_add_handle($master, $ch);     }      do {         while (($execrun = curl_multi_exec($master, $running)) == CURLM_CALL_MULTI_PERFORM);         if ($execrun != CURLM_OK) {             break;         }          // a request was just completed -- find out which one         while ($done = curl_multi_info_read($master)) {             $info = curl_getinfo($done['handle']);             if ($info['http_code'] == 200) {                 $output = curl_multi_getcontent($done['handle']);                  // request successful.  process output using the callback function.                 $callback($output);                  // start a new request (it's important to do this before removing the old one)                 $ch                   = curl_init();                 $options[CURLOPT_URL] = $urls[$i++]; // increment i                 curl_setopt_array($ch, $options);                 curl_multi_add_handle($master, $ch);                  // remove the curl handle that just completed                 curl_multi_remove_handle($master, $done['handle']);             } else {                 // request failed.  add error handling.             }         }     } while ($running);      curl_multi_close($master);     return true; }

修改一下。只要在新增url的時候加個判斷就好了。// 當(dāng)$i等于$urls數(shù)組大小時不用再增加了。

function rolling_curl($urls, $callback, $custom_options = null) {//多個url訪問      // make sure the rolling window isn't greater than the # of urls     $rolling_window = 5;     $rolling_window = (sizeof($urls) < $rolling_window) ? sizeof($urls) : $rolling_window;      $master   = curl_multi_init();     $curl_arr = array();      // add additional curl options here     $std_options = array(         CURLOPT_RETURNTRANSFER => true,         CURLOPT_FOLLOWLOCATION => true,         CURLOPT_MAXREDIRS      => 5         );     $options = ($custom_options) ? ($std_options + $custom_options) : $std_options;      // start the first batch of requests     for ($i = 0; $i < $rolling_window; $i++) {         $ch                   = curl_init();         $options[CURLOPT_URL] = $urls[$i];         curl_setopt_array($ch, $options);         curl_multi_add_handle($master, $ch);     }      do {         while (($execrun = curl_multi_exec($master, $running)) == CURLM_CALL_MULTI_PERFORM);         if ($execrun != CURLM_OK) {             break;         }          // a request was just completed -- find out which one         while ($done = curl_multi_info_read($master)) {             $info = curl_getinfo($done['handle']);             if ($info['http_code'] == 200) {                 $output = curl_multi_getcontent($done['handle']);                  // request successful.  process output using the callback function.                 $callback($output);                  // start a new request (it's important to do this before removing the old one)                 // 當(dāng)$i等于$urls數(shù)組大小時不用再增加了                 if($i<sizeof($urls)){                     $ch                   = curl_init();                     $options[CURLOPT_URL] = $urls[$i++]; // increment i                     curl_setopt_array($ch, $options);                     curl_multi_add_handle($master, $ch);                 }                 // remove the curl handle that just completed                 curl_multi_remove_handle($master, $done['handle']);             } else {                 // request failed.  add error handling.             }         }     } while ($running);      curl_multi_close($master);     return true; }

以上，結(jié)束。記錄一下，以免自己忘記。