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 && $mrc == CURLM_OK) {// wait for networkif (curl_multi_select($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
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

原文地址：http://www.searchtb.com/2010/12/using-multicurl-to-improve-performance.html?spm=0.0.0.0.onjnnY