前端开发中的性能那点事（二）巧用curl 并发减少后端访问时间-优快云博客

本文介绍如何使用PHP的curl多路复用功能实现并发请求多个HTTP接口，通过对比单个顺序请求的方式，展示了并发请求能够显著减少页面加载时间，提高整体效率。

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前言：
在我们平时的程序中难免出现同时访问几个接口的情况，平时我们用curl进行访问的时候，一般都是单个、顺序访问，假如有3个接口，每个接口耗时500毫秒那么我们三个接口就要花费1500毫秒了，这个问题太头疼了严重影响了页面访问速度，有没有可能并发访问来提高速度呢？今天就简单的说一下，利用curl并发来提高页面访问速度，
希望大家多指导。
1、老的curl访问方式以及耗时统计

          <?php 
        
          functioncurl_fetch($url,$timeout=3){ 
        
              $ch= curl_init(); 
        
              curl_setopt($ch, CURLOPT_URL,$url); 
        
              curl_setopt($ch, CURLOPT_TIMEOUT,$timeout); 
        
              curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
        
              $data= curl_exec($ch); 
        
              $errno= curl_errno($ch); 
        
              if($errno>0) { 
        
                  $data= false; 
        
              } 
        
              curl_close($ch); 
        
              return$data; 
        
          } 
        
          functionmicrotime_float() 
        
          { 
        
             list($usec,$sec) =explode(" ", microtime()); 
        
             return((float)$usec+ (float)$sec); 
        
          } 
        
          $url_arr=array( 
        
               "taobao"=>" 
         http://www.taobao.com", 
        
               "sohu"=>" 
         http://www.sohu.com", 
        
               "sina"=>" 
         http://www.sina.com.cn", 
        
               ); 
        
           $time_start= microtime_float(); 
        
           $data=array(); 
        
           foreach($url_arras$key=>$val) 
        
           { 
        
               $data[$key]=curl_fetch($val); 
        
           } 
        
           $time_end= microtime_float(); 
        
           $time=$time_end-$time_start; 
        
           echo"耗时:{$time}"; 
        
          ?>

耗时:0.614秒
2、curl并发访问方式以及耗时统计

          <?php 
        
          functioncurl_multi_fetch($urlarr=array()){ 
        
              $result=$res=$ch=array(); 
        
              $nch= 0; 
        
              $mh= curl_multi_init(); 
        
              foreach($urlarras$nk=>$url) { 
        
                  $timeout=2; 
        
                  $ch[$nch] = curl_init(); 
        
                  curl_setopt_array($ch[$nch],array( 
        
                  CURLOPT_URL =>$url, 
        
                  CURLOPT_HEADER => false, 
        
                  CURLOPT_RETURNTRANSFER => true, 
        
                  CURLOPT_TIMEOUT =>$timeout, 
        
                  )); 
        
                  curl_multi_add_handle($mh,$ch[$nch]); 
        
                  ++$nch; 
        
              } 
        
              /* wait for performing request */ 
        
              do{ 
        
                  $mrc= curl_multi_exec($mh,$running); 
        
              }while(CURLM_CALL_MULTI_PERFORM ==$mrc); 
        
              while($running&&$mrc== CURLM_OK) { 
        
                  // wait for network 
        
                  if(curl_multi_select($mh, 0.5) > -1) { 
        
                      // pull in new data; 
        
                      do{ 
        
                          $mrc= curl_multi_exec($mh,$running); 
        
                      }while(CURLM_CALL_MULTI_PERFORM ==$mrc); 
        
                  } 
        
              } 
        
              if($mrc!= CURLM_OK) { 
        
                  error_log("CURL Data Error"); 
        
              } 
        
              /* get data */ 
        
              $nch= 0; 
        
              foreach($urlarras$moudle=>$node) { 
        
                  if(($err= curl_error($ch[$nch])) =='') { 
        
                      $res[$nch]=curl_multi_getcontent($ch[$nch]); 
        
                      $result[$moudle]=$res[$nch]; 
        
                  } 
        
                  else 
        
                  { 
        
                      error_log("curl error"); 
        
                  } 
        
                  curl_multi_remove_handle($mh,$ch[$nch]); 
        
                  curl_close($ch[$nch]); 
        
                  ++$nch; 
        
              } 
        
              curl_multi_close($mh); 
        
              return $result; 
        
          } 
        
          $url_arr=array( 
        
               "taobao"=>" 
         http://www.taobao.com", 
        
               "sohu"=>" 
         http://www.sohu.com", 
        
               "sina"=>" 
         http://www.sina.com.cn", 
        
               ); 
        
          functionmicrotime_float() 
        
          { 
        
             list($usec,$sec) =explode(" ", microtime()); 
        
             return((float)$usec+ (float)$sec); 
        
          } 
        
          $time_start= microtime_float(); 
        
          $data=curl_multi_fetch($url_arr); 
        
          $time_end= microtime_float(); 
        
          $time=$time_end-$time_start; 
        
           echo"耗时:{$time}"; 
        
          ?>

耗时:0.316秒
帅气吧整个页面访问后端接口的时间节省了一半
3、curl相关参数
来自：http://cn2.php.net/manual/en/ref.curl.php
curl_close — Close a cURL session
curl_copy_handle — Copy a cURL handle along with all of its preferences
curl_errno — Return the last error number
curl_error — Return a string containing the last error for the current session
curl_exec — Perform a cURL session
curl_getinfo — Get information regarding a specific transfer
curl_init — Initialize a cURL session
curl_multi_add_handle — Add a normal cURL handle to a cURL multi handle
curl_multi_close — Close a set of cURL handles
curl_multi_exec — Run the sub-connections of the current cURL handle
curl_multi_getcontent — Return the content of a cURL handle if CURLOPT_RETURNTRANSFER is set
curl_multi_info_read — Get information about the current transfers
curl_multi_init — Returns a new cURL multi handle
curl_multi_remove_handle — Remove a multi handle from a set of cURL handles
curl_multi_select — Wait for activity on any curl_multi connection
curl_setopt_array — Set multiple options for a cURL transfer
curl_setopt — Set an option for a cURL transfer
curl_version — Gets cURL version information