function fetchAndProcessUrls(array $urls, callable $f) {
 
    $multi = curl_multi_init();
    $reqs  = [];
 
    foreach ($urls as $url) {
        $req = curl_init();
        curl_setopt($req, CURLOPT_URL, $url);
        curl_setopt($req, CURLOPT_RETURNTRANSFER, true);
        curl_multi_add_handle($multi, $req);
        $reqs[] = $req;
    }
 
    // While we're still active, execute curl
    $active = null;
 
    // Execute the handles
    do {
        $mrc = curl_multi_exec($multi, $active);
    } while ($mrc == CURLM_CALL_MULTI_PERFORM);
 
    while ($active && $mrc == CURLM_OK) {
        if (curl_multi_select($multi) != -1) {
            do {
                $mrc = curl_multi_exec($multi, $active);
            } while ($mrc == CURLM_CALL_MULTI_PERFORM);
        }
    }
 
    // Close the handles
    foreach ($reqs as $req) {
        $f(curl_multi_getcontent($req));
        curl_multi_remove_handle($multi, $req);
    }
    curl_multi_close($multi);
}
$toplamSayfaSayisi=50;

$urlArray=Array();

for($sayfa=0;$sayfa<=$toplamSayfaSayisi;$sayfa++) {
$url='http://site.com/content.php?page='.$sayfa;

array.push($urlArray,$url);
}


fetchAndProcessUrls($urlArray, function($data) { 
    echo $data;
}