无法远程下载多个网址

Question

我正在使用fopen和fwrite下载远程网址。一个工作正常，但是当我使用多个网址时，只会下载第一个。

foreach($urls as $url) {
    $filename = $core->getFileDestination($url);
    $urlsize = $core->getUrlFileSize($url);
    if (isset($_POST['downloaded'])){
        $fileSize = filesize($filename);
        $newfsize = $core->formatSize($fileSize);
        $newurlsize = $core->formatSize($urlsize);
        echo $filename." - ".$newfsize." / ".$newurlsize."<br>";
    }
    else{
        $file = fopen ($url, "rb");
        if ($file) {
            $newf = fopen ($filename, "wb");

            if ($newf)
            while(!feof($file)) {
                fwrite($newf, fread($file, 1024 * 8 ), 1024 * 8 );
            }
        }
        if ($file) {
            fclose($file);
        }
        if ($newf) {
            fclose($newf);
        }
        echo "done";
    }
}