New submission from Tim Burgess <ozburg...@gmail.com>:
Retrieving and using a module directly from sys.modules (from C in this case) leads to a race condition where the module may be importing on another thread but has not yet been initialised. For slow filesystems or large modules (e.g. numpy) this seems to lead to easily reproducible errors (the attached code fails 100% of the time on my work machine - CentOS 7). I believe they have to be in sys.modules during this phase due to the possibility of circular references. importlib handles this carefully with locking, but _pickle.c bypasses all that, leading to issues with threaded codes that use pickling, e.g. dask/distributed. ---------- components: Extension Modules files: reproducer_submit.py messages: 324528 nosy: tjb900 priority: normal severity: normal status: open title: C unpickling bypasses import thread safety type: crash versions: Python 3.6, Python 3.7, Python 3.8 Added file: https://bugs.python.org/file47784/reproducer_submit.py _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue34572> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
