php析构函数疑惑

<?phpclass Test {    public $start;    public $end;        public function __construct() {        echo "__construct<br />";        $this->start = microtime(true);    }        public function test() {        echo "in test()<br />";        throw new Exception("error", 500); // 抛出异常     }        public function __destruct() {        echo "__destruct<br />";    }}$test = new Test();$test->test();

方法里抛出异常后，不会调用析构函数：

try异常后能调用析构函数：

<?phpclass Test {    public $start;    public $end;        public function __construct() {        echo "__construct<br />";        $this->start = microtime(true);    }        public function test() {        echo "in test()<br />";        try { // try 异常            throw new Exception("error", 500); // 抛出异常         } catch(Exception $e) {        }    }        public function __destruct() {        echo "__destruct<br />";    }}$test = new Test();$test->test();