php 数据过大 内存溢出

Fatal error: Allowed memory size of 8388608 bytes exhausted (tried to allocate 92160 bytes) in :\Inetpub\wwwroot04\test.php on line 8
Fatal error: Out of memory (allocated 259,260,416) (tried to allocate 16 bytes) in C:\Inetpub\wwwroot04\test.php on line 8
//ini_set('memory_limit', '-1');
$index=0;
$arr = array();
try {
    while (true) {
        $arr[] = $index++;
    }
} catch (Exception $e) {
    exit($index);
}