请教大神curl_mutil的问题

跑的时候，在这个if这里，老不进去，就一直while循环，
这是为何？

function async_get_url($url_array, $wait_usec = 0)
{
$t1 = get_time();
if (!is_array($url_array))
{return false;}
//设置每个请求等待时间，ms记
$wait_usec = intval($wait_usec);
//最后取数据
$data = array();
//批量句柄
$handle = array();
//剩余要抓的地址
$running = 0;
//定义批处理句柄
$mh = curl_multi_init(); // multi curl handler
//配置
$curl_option = array(
CURLOPT_HEADER=>0,
CURLOPT_RETURNTRANSFER=>1,
CURLOPT_TIMEOUT=>10,
CURLOPT_USERAGENT=>'Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)',
CURLOPT_FOLLOWLOCATION=>1,
CURLOPT_MAXREDIRS=>7,
);
foreach ($url_array as $i=>$url)
{
//分别为每个地址初始化句柄
$handle[$i] = curl_init();
//设置配置
curl_setopt($handle[$i], CURLOPT_URL, $url);
curl_setopt_array($handle[$i], $curl_option);
// 把 curl resource 放进 multi curl handler 里
curl_multi_add_handle($mh, $handle[$i]);
}
$z = 1;
do{
$t2 = get_time();
echo "\r\n在抓第{$z}次\r\n";
get_memory();
get_peak_memory();
//多线程执行
$a = curl_multi_exec($mh, $running);
echo "还剩{$running}个地址\r\n";
$t3 = get_time();
echo $a."\r\n";
echo CURLM_CALL_MULTI_PERFORM."\r\n";
echo "\r\n";
echo "此次用时".($t3-$t2)."S\r\n已经用时".($t3-$t1)." S";
$z++;
//} while ($running > 0);
}while($a == CURLM_CALL_MULTI_PERFORM);
echo "\r\n";
echo $running."\r\n";//14
echo $a."\r\n";//0
echo CURLM_CALL_MULTI_PERFORM."\r\n";//-1
echo CURLM_OK."\r\n";//0
echo curl_multi_select($mh)."\r\n";//-1
echo "\r\n";
while($running && $a == CURLM_OK)
{
echo "aaaaaaaaaa\r\n";
if (curl_multi_select($mh) != -1)
{
echo "bbbbbbbbbbbbb\r\n";
do{
echo "cccccccccccc\r\n";
$a = curl_multi_exec($mh, $running);
}while($a == CURLM_CALL_MULTI_PERFORM);
}
echo "dddddddddddd\r\n";
}
//读取抓的数据
foreach ($handle as $i => $ch)
{
$content = curl_multi_getcontent($ch);
$data[$i] = (curl_errno($ch) == 0) ? $content : false;
echo "放第".($i+1)."张\r\n";
$name = './img/'.$i.".jpg";
file_put_contents($name, $content);
curl_multi_remove_handle($mh, $handle[$i]);
}
curl_multi_close($mh);
//return $data;
}

没人吗