New submission from Pablo Galindo Salgado <pablog...@gmail.com>:
A weak reference may try to invoke a callback object that is being cleaned (tp_clear) by the garbage collector and it may be in an inconsistent state. As the garbage collector explicitly does not invoke callbacks that are part of the same cycle isolate as the weak reference (pretending that the weak reference was destroyed first), we should act in the same way when invoking callbacks using Objects/weakrefobject.c:handle_callback. For example, consider the following scenario: - F is a function. - An object O is in a cycle with F. - O has a weak reference with F as a callback. When running the garbage collector, is possible to end in Objects/weakrefobject.c:handle_callback if the tp_clear of F decrements the references of O, invoking the weak reference callback that will try to call F, which is in an incosistent state as is in the middle of its tp_clear and some internal fields may be NULL. ---------- components: Interpreter Core messages: 351001 nosy: pablogsal, pitrou, vstinner priority: normal severity: normal status: open title: Handle weakreference callbacks invoked indirectly in the middle of a gc collection versions: Python 3.7, Python 3.8, Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue38009> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
