New submission from Gregory P. Smith <g...@krypto.org>:
I'm spawning a dicussion buried in the way too long thread of https://bugs.python.org/issue6721 over here into its own specific issue to treat as a 3.7 release blocker for a rollback or repair decision before 3.7.4. https://github.com/python/cpython/commit/3b699932e5ac3e76031bbb6d700fbea07492641d I believe that was released in 3.7.1 is leading to a behavior regression for an application (the Fedora installer's libreswan kvmrunner?). Full details can be found in the messages of the other issue starting with: https://bugs.python.org/issue6721#msg329474 TL;DR - logging.Handler instances each have their own threading.Rlock. libreswan implements at least one logging.Handler subclass. That subclass's custom emit() implementation directly calls potentially many other sub-handlers emit() methods. Some of those emit() methods (such as logging.StreamHandler) call flush() which acquires the handler's lock. So they've got a dependency between these two locks, the first's must be acquired before the second. But the logging module APIs have no concept of sub-handlers and lock ordering. I see many flaws with the libreswan code's design (I'm already ignoring the futility of threading + fork) but this still caused a behavior regression in the stable 3.7 release. (more comments coming as followups to avoid a wall of text with too many topics) ---------- assignee: gregory.p.smith components: Library (Lib) keywords: 3.7regression messages: 339472 nosy: cagney, gregory.p.smith, ned.deily, vstinner priority: release blocker severity: normal status: open title: logging regression with threading + fork are mixed in 3.7.1rc2 (deadlock potential) type: behavior versions: Python 3.7 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue36533> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
