https://github.com/python/cpython/commit/48d9823a0ebde4dfab8bc154bb6df462fb2... commit: 48d9823a0ebde4dfab8bc154bb6df462fb2ee403 branch: master author: Allen W. Smith, Ph.D <drallensmith@users.noreply.github.com> committer: Antoine Pitrou <pitrou@free.fr> date: 2017-08-12T17:37:09+02:00 summary: bpo-5001, bpo-31169: Fix two uninformative asserts in multiprocessing/managers.py (#3078) * Make error message more informative Replace assertions in error-reporting code with more-informative version that doesn't cause confusion over where and what the error is. * Additional clarification + get travis to check * Change from SystemError to TypeError As suggested in PR comment by @pitrou, changing from SystemError; TypeError appears appropriate. * NEWS file installation; ACKS addition (will do my best to justify it by additional work) files: A Misc/NEWS.d/next/Library/2017-08-12-09-25-55.bpo-5001.huQi2Y.rst M Lib/multiprocessing/managers.py M Misc/ACKS diff --git a/Lib/multiprocessing/managers.py b/Lib/multiprocessing/managers.py index cae1c10734b..c6722771b05 100644 --- a/Lib/multiprocessing/managers.py +++ b/Lib/multiprocessing/managers.py @@ -84,14 +84,17 @@ def dispatch(c, id, methodname, args=(), kwds={}): def convert_to_error(kind, result): if kind == '#ERROR': return result - elif kind == '#TRACEBACK': - assert type(result) is str - return RemoteError(result) - elif kind == '#UNSERIALIZABLE': - assert type(result) is str - return RemoteError('Unserializable message: %s\n' % result) + elif kind in ('#TRACEBACK', '#UNSERIALIZABLE'): + if not isinstance(result, str): + raise TypeError( + "Result {0!r} (kind '{1}') type is {2}, not str".format( + result, kind, type(result))) + if kind == '#UNSERIALIZABLE': + return RemoteError('Unserializable message: %s\n' % result) + else: + return RemoteError(result) else: - return ValueError('Unrecognized message type') + return ValueError('Unrecognized message type {!r}'.format(kind)) class RemoteError(Exception): def __str__(self): diff --git a/Misc/ACKS b/Misc/ACKS index d6088b3f5d9..6fc41b36b59 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -1465,6 +1465,7 @@ Ville Skyttä Michael Sloan Nick Sloan Václav Šmilauer +Allen W. Smith Christopher Smith Eric V. Smith Gregory P. Smith diff --git a/Misc/NEWS.d/next/Library/2017-08-12-09-25-55.bpo-5001.huQi2Y.rst b/Misc/NEWS.d/next/Library/2017-08-12-09-25-55.bpo-5001.huQi2Y.rst new file mode 100644 index 00000000000..f157d49a816 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2017-08-12-09-25-55.bpo-5001.huQi2Y.rst @@ -0,0 +1,9 @@ +There are a number of uninformative asserts in the `multiprocessing` module, +as noted in issue 5001. This change fixes two of the most potentially +problematic ones, since they are in error-reporting code, in the +`multiprocessing.managers.convert_to_error` function. (It also makes more +informative a ValueError message.) The only potentially problematic change +is that the AssertionError is now a TypeError; however, this should also +help distinguish it from an AssertionError being *reported* by the +function/its caller (such as in issue 31169). - Patch by Allen W. Smith +(drallensmith on github).