I tried Daniel G Zylberberg's function and
it was not working the way it was posted.
I made some changes to get it work and here is what I use:

function multiCurl($res, $options=""){

        if(count($res)<=0) return False;

        $handles = array();

        if(!$options) // add default options
            $options = array(
                CURLOPT_HEADER=>0,
                CURLOPT_RETURNTRANSFER=>1,
            );

        // add curl options to each handle
        foreach($res as $k=>$row){
            $ch{$k} = curl_init();
            $options[CURLOPT_URL] = $row['url'];
            $opt = curl_setopt_array($ch{$k}, $options);
            var_dump($opt);
            $handles[$k] = $ch{$k};
        }

        $mh = curl_multi_init();

        // add handles
        foreach($handles as $k => $handle){
            $err = curl_multi_add_handle($mh, $handle);            
        }

        $running_handles = null;

        do {
          curl_multi_exec($mh, $running_handles);
          curl_multi_select($mh);
        } while ($running_handles > 0);
       
        foreach($res as $k=>$row){
            $res[$k]['error'] = curl_error($handles[$k]);
            if(!empty($res[$k]['error']))
                $res[$k]['data']  = '';
            else
                $res[$k]['data']  = curl_multi_getcontent( $handles[$k] );  // get results

            // close current handler
            curl_multi_remove_handle($mh, $handles[$k] );
        }
        curl_multi_close($mh);
        return $res; // return response
}