[issue13842] Cannot pickle Ellipsis or NotImplemented
New submission from James Sanders : At present, the built-in constants Ellipsis (...) and NotImplemented cannot be pickled. Perhaps there is a good reason for this, but the only discussion I can find is at msg<108957>, where it is stated that these values (along with their types, and type(None)) cannot be pickled. I ran across this in a class that keeps track of numpy-style slicing operations, and so sometimes stores references to Ellipsis. While this is easy to work around, it does seem a little surprising that ... cannot be pickled, when slice objects can be. I don't know if there is a likely use for pickling NotImplemented. If this is not changed, perhaps it could be explicitly stated in the documentation that these objects cannot be pickled? -- messages: 151838 nosy: James.Sanders, alexandre.vassalotti, pitrou priority: normal severity: normal status: open title: Cannot pickle Ellipsis or NotImplemented type: enhancement versions: Python 3.3 ___ Python tracker <http://bugs.python.org/issue13842> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue13842] Cannot pickle Ellipsis or NotImplemented
James Sanders added the comment: I've submitted a patch that just uses save_global to pickle Ellipsis and NotImplemented, so the resulting pickle should be unpicklable anywhere. I'm completely new to the C API so not sure if the way I am building python strings (to pass to save_global) is correct, but it seems to work. -- keywords: +patch Added file: http://bugs.python.org/file24315/pickling_ellipsis_notimplemented.patch ___ Python tracker <http://bugs.python.org/issue13842> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5527] multiprocessing won't work with Tkinter (under Linux)
James Sanders added the comment: I recently got hit by this bug on 64-bit ubuntu 13.04, with python 3.3.1 and tcl/tk 8.5.13 installed from the Ubuntu repositories. However, I tried building the same versions of tcl, tk, and python locally, and couldn't reproduce the bug. I also built python 3.3.2 with several releases of tcl/tk. With 8.5.8 and earlier, I get a buffer overflow. With 8.5.9-14 and recent trunk versions of tk and tcl, everything works. With 8.6.0, I get the hang. In the tcl/tk versions where the script works correctly, if I also have some tkinter code (such as instantiating a Tk and a Button) in the main process before the fork, then I sometimes get a crash with one of several different weird error messages from X, but this is very inconsistent. The direct cause of the bug seems to be the call to Tcl_FindExecutable in _tkinter's initialization code, which tells tcl the path of the python executable, but as a side effect triggers tcl into running some initialization routines earlier than it would do otherwise. Removing this call (which doesn't seem to have any adverse effects on my system) appears to "fix" the bug, but if anything else triggers tcl's initialization code before the fork (such as instantiating a tkinter.Tk object), the hang returns. I'm not really sure where else to go with this. I've attached a simplified python-3-compatible script displaying the problem in case someone else wants to have a look. -- nosy: +James.Sanders versions: +Python 2.7, Python 3.3, Python 3.4 -Python 2.6 Added file: http://bugs.python.org/file31222/hanger.py ___ Python tracker <http://bugs.python.org/issue5527> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5527] multiprocessing won't work with Tkinter (under Linux)
James Sanders added the comment: I did a bit more digging and I think I've worked out what is going on. The particular bit of tcl initialization code that triggers the problem if it is run before the fork is Tcl_InitNotifier in tclUnixNotify.c. It turns out there is a known problem with this bit of tcl not being process-safe if tcl was built with threading support (this is discussed at https://bugs.archlinux.org/task/16401, for example). The bug doesn't show up in my 8.5 builds as threading support is off by default, though the debian/ubuntu packages apparently have it switched on. Threading was turned on by default in 8.6, but a recent change to tclUnixNotify.c (discussed at https://issues.apache.org/bugzilla/show_bug.cgi?id=55153#c13 - it should be included in 8.6.1 and 8.5.15) appears to have fixed the whole problem anyway. So hopefully the bug should disappear entirely in future releases of tcl, but for now you can work around it by building tcl without threads, calling exec in between the fork and any use of tkinter in the child process, or not importing tkinter until after the fork. I don't know if there should be a note about this somewhere in the tkinter docs? -- ___ Python tracker <http://bugs.python.org/issue5527> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
