CURL_MULTI active maximum tracking

Question

sry for my not the best english:) So i work with curl_multi.

do {
    $mrc = curl_multi_exec($this->curl, $active);
}
while ($mrc == CURLM_CALL_MULTI_PERFORM);

while ($active && $mrc == CURLM_OK) {
    if (curl_multi_select($this->curl) != -1) {
        do {
            $mrc = curl_multi_exec($this->curl, $active);
        } while ($mrc == CURLM_CALL_MULTI_PERFORM);
    }
}

When i track $active, maximum value is 1019 (even if i have for example 2000 requests).