利用curl并发来提高页面访问速度

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

function curl_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;

}

function microtime_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_arr as $key=>$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

function curl_multi_fetch($urlarr=array()){

    $result=$res=$ch=array();

    $nch = 0;

    $mh = curl_multi_init();

    foreach ($urlarr as $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 ($urlarr as $moudle=>$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",

     );

function microtime_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}";

?>

输出结果array('taobao'=>result,'sina'=>result,'baidu'=>result)　　;

耗时:0.316秒

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