Mailing List Archive: [issue1672332] cPickle cannot unpickle subnormal floats on some machines

[issue1672332] cPickle cannot unpickle subnormal floats on some machines

Jan 5, 2009, 7:19 AM

Post #1 of 7 (451 views)

Mark Dickinson <dickinsm@gmail.com> added the comment:

Change title; this has nothing to do with 64 bit.

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title: cPickle can pickle, but cannot unpickle on 64bit machines -> cPickle cannot unpickle subnormal floats on some machines

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[issue1672332] cPickle cannot unpickle subnormal floats on some machines [ In reply to ]

Jan 16, 2009, 2:35 AM

Post #2 of 7 (408 views)

Mark Dickinson <dickinsm@gmail.com> added the comment:

Here's a patch, against the trunk, that simply amends load_float to ignore
errno on underflow (while retaining it on overflow). This fixes the problem on my machine.

The added tests may be a little severe. There's no *good* reason why
dumping and then loading a float on the same machine shouldn't produce
exactly the same value, but there are likely many bad reasons. I propose
to checkin the change and watch the buildbots carefully; if there are
failures I'll weaken the tests to check for approximate equality instead
of exact equality.

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keywords: +patch
Added file: http://bugs.python.org/file12762/issue1672332.patch

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[issue1672332] cPickle cannot unpickle subnormal floats on some machines [ In reply to ]

Jan 24, 2009, 9:00 AM

Post #3 of 7 (407 views)

Mark Dickinson <dickinsm@gmail.com> added the comment:

Fixed in the trunk in r68903. If the buildbots are happy with the new
tests, I'll port to 2.6, 3.0 and 3.1.

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versions: -Python 2.7

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[issue1672332] cPickle cannot unpickle subnormal floats on some machines [ In reply to ]

Jan 24, 2009, 11:07 AM

Post #4 of 7 (396 views)

Mark Dickinson <dickinsm@gmail.com> added the comment:

Hmm. After checking in this patch, the gentoo x86 trunk buildbot
has a new failure in test_pickletools, with the following output:

test_pickletools
**********************************************************************
File "/home/buildslave/python-trunk/trunk.norwitz-x86/build/Lib/pickletools.py", line ?, in
pickletools.__test__.disassembler_test
Failed example:
dis(pickle.dumps(random.random, 0))
Expected:
0: c GLOBAL 'random random'
15: p PUT 0
18: . STOP
highest protocol among opcodes = 0
Got:
0: c GLOBAL 'bsddb.test.test_thread random'
31: p PUT 0
34: . STOP
highest protocol among opcodes = 0
**********************************************************************
1 items had failures:
1 of 25 in pickletools.__test__.disassembler_test
***Test Failed*** 1 failures.
test test_pickletools failed -- 1 of 95 doctests failed

I'm having some difficulty figuring out how this could be
related to the checkin of this patch.

Anyone have any ideas where this might be coming from?

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[issue1672332] cPickle cannot unpickle subnormal floats on some machines [ In reply to ]

Jan 24, 2009, 11:54 AM

Post #5 of 7 (406 views)

Antoine Pitrou <pitrou@free.fr> added the comment:

This is not a new failure but an erratic one, and caused by a weakness
in pickle's handling of functions. See #3657.

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nosy: +pitrou

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[issue1672332] cPickle cannot unpickle subnormal floats on some machines [ In reply to ]

Jan 24, 2009, 11:59 AM

Post #6 of 7 (400 views)

Mark Dickinson <dickinsm@gmail.com> added the comment:

Thanks, Antoine!

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[issue1672332] cPickle cannot unpickle subnormal floats on some machines [ In reply to ]

Jan 24, 2009, 1:49 PM

Post #7 of 7 (398 views)

Mark Dickinson <dickinsm@gmail.com> added the comment:

Fix merged in r68907 (2.6), r68908 (3.1) and r68909 (3.0).

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resolution: -> fixed
status: open -> closed

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