ya untungnya ada penjelasan ini: https://S E N S O R@johann.pardanaud/about-circular-references-in-php-10f71f811e9
masuk akal lah, kan sudah beralih ke concurrent cycle Collection. Penjelasannya detailnya di sini: https://www.php.net/manual/en/features.gc.refcounting-basics.php#features.gc.cleanup-problems https://researcher.watson.ibm.com/researcher/files/us-bacon/Bacon01Concurrent.pdf