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changeset: 99207:5d88c1d413b9 branch: 2.7 parent: 99196:106c49edbb12 user: Nick Coghlan ncoghlan@gmail.com date: Thu Nov 19 12:59:39 2015 +1000 files: Lib/multiprocessing/forking.py Misc/NEWS description: Close #10128: don't rerun __main__.py in multiprocessing - backports issue #10845's mitigation of incompatibilities between the multiprocessing module and directory and zipfile execution - Multiprocessing on Windows will now automatically skip rerunning top level __main__.py modules in spawned processes, rather than failing with AssertionError diff -r 106c49edbb12 -r 5d88c1d413b9 Lib/multiprocessing/forking.py --- a/Lib/multiprocessing/forking.py Wed Nov 18 00:59:17 2015 +0000 +++ b/Lib/multiprocessing/forking.py Thu Nov 19 12:59:39 2015 +1000 @@ -470,12 +470,26 @@ process.ORIGINAL_DIR = data['orig_dir'] if 'main_path' in data: + # XXX (ncoghlan): The following code makes several bogus + # assumptions regarding the relationship between __file__ + # and a module's real name. See PEP 302 and issue #10845 + # The problem is resolved properly in Python 3.4+, as + # described in issue #19946 + main_path = data['main_path'] main_name = os.path.splitext(os.path.basename(main_path))[0] if main_name == '__init__': main_name = os.path.basename(os.path.dirname(main_path)) - if main_name != 'ipython': + if main_name == '__main__': + # For directory and zipfile execution, we assume an implicit + # "if __name__ == '__main__':" around the module, and don't + # rerun the main module code in spawned processes + main_module = sys.modules['__main__'] + main_module.__file__ = main_path + elif main_name != 'ipython': + # Main modules not actually called __main__.py may + # contain additional code that should still be executed import imp if main_path is None: diff -r 106c49edbb12 -r 5d88c1d413b9 Misc/NEWS --- a/Misc/NEWS Wed Nov 18 00:59:17 2015 +0000 +++ b/Misc/NEWS Thu Nov 19 12:59:39 2015 +1000 @@ -55,6 +55,11 @@ Library ------- +- Issue #10128: backport issue #10845's mitigation of incompatibilities between + the multiprocessing module and directory and zipfile execution. + Multiprocessing on Windows will now automatically skip rerunning __main__ in + spawned processes, rather than failing with AssertionError. + - Issue #25578: Fix (another) memory leak in SSLSocket.getpeercer(). - Issue #25590: In the Readline completer, only call getattr() once per /ncoghlan@gmail.com