如何将单线程的curl_multi_init改造成多线程并发请求？

function post($url, $data = '', $head = 'application/x-www-form-urlencoded'){    // ...    $output = curl_exec($ch);    curl_close($ch);    return $output;}

$newData = array_chunk($data, 10, true);foreach ($newData as $k => $tmp) {    $mh = curl_multi_init();    $chs = [];    foreach ($tmp as $key => $url) {        $ch = curl_init();        $chs[$key] = $ch;        // ...        curl_setopt($ch, CURLOPT_POST, 1);        curl_setopt($ch, CURLOPT_POSTFIELDS, $tmp);        curl_multi_add_handle($mh, $ch);    }    $active = null;    do {        $mrc = curl_multi_exec($mh, $active);    } while ($mrc == CURLM_CALL_MULTI_PERFORM);    while ($active && $mrc == CURLM_OK) {        if (curl_multi_select($mh) != -1) {            do {                $mrc = curl_multi_exec($mh, $active);            } while ($mrc == CURLM_CALL_MULTI_PERFORM);        }    }    foreach ($chs as $key => $ch) {        $res[$k][$key] = curl_multi_getcontent($ch);        curl_multi_remove_handle($mh, $ch);    }    curl_multi_close($mh);}var_dump($res);