importing umath_tests and then CTRL-D crashes with core dump (Trac #1425) #2023

thouis · 2012-10-19T21:01:50Z

Original ticket http://projects.scipy.org/numpy/ticket/1425 on 2010-03-10 by @johannct, assigned to unknown.

[cohen@jarrett core]$ python

Python 2.6.2 (r262:71600, Jan 25 2010, 18:46:45) [GCC 4.4.2 20091222
(Red Hat 4.4.2-20)] on linux2 Type "help", "copyright", "credits" or
"license" for more information.

import umath_tests

python: Modules/gcmodule.c:277: visit_decref: Assertion `gc->gc.gc_refs
!= 0' failed.
Aborted (core dumped)

This occurs on my Fedora 12 box with python 2.6.2 and numpy 2.0.0.dev8291

numpy-gitbot · 2012-10-23T02:43:06Z

@johannct wrote on 2010-03-10

backtrace of a python session that exhibits this crash:
(gdb) bt
#0 0x004a1416 in __kernel_vsyscall ()
#1 0x00609a91 in raise (sig=6) at
../nptl/sysdeps/unix/sysv/linux/raise.c:64
#2 0x0060b35a in abort () at abort.c:92
#3 0x00602be8 in __assert_fail (assertion=,
file=, line=, function=)
at assert.c:81
#4 0x0032e31e in visit_decref (op=, data=) at Modules/gcmodule.c:277
#5 0x002a18c2 in dict_traverse (op=, visit=, arg=) at Objects/dictobject.c:2003
#6 0x0032eaf3 in subtract_refs (generation=) at
Modules/gcmodule.c:296
#7 collect (generation=) at Modules/gcmodule.c:817
#8 0x0032f640 in PyGC_Collect () at Modules/gcmodule.c:1292
#9 0x003200f0 in Py_Finalize () at Python/pythonrun.c:424
#10 0x00320218 in Py_Exit (sts=) at
Python/pythonrun.c:1714
#11 0x00320367 in handle_system_exit () at Python/pythonrun.c:1116
#12 0x0032057d in PyErr_PrintEx (set_sys_last_vars=) at Python/pythonrun.c:1126
#13 0x0032079f in PyErr_Print () at Python/pythonrun.c:1035
#14 0x00320f9a in PyRun_InteractiveOneFlags (fp=,
filename=, flags=) at
Python/pythonrun.c:843
#15 0x00321093 in PyRun_InteractiveLoopFlags (fp=,
filename=, flags=0xbfffefec) at Python/pythonrun.c:760
#16 0x003211df in PyRun_AnyFileExFlags (fp=,
filename=0x365add "", closeit=, flags=)
at Python/pythonrun.c:729
#17 0x0032dc85 in Py_Main (argc=, argv=) at Modules/main.c:599
#502 0x080485c8 in main (argc=, argv=) at Modules/python.c:23

numpy-gitbot · 2012-10-23T02:43:06Z

@pv wrote on 2010-03-10

More discussion here:
http://permalink.gmane.org/gmane.comp.python.numeric.general/36831

Current best guess: some sort of refcounting error in the generalized ufunc code, maybe?

numpy-gitbot · 2012-10-23T02:43:07Z

@bsouthey wrote on 2010-03-10

This occurred in changeset 8262, specifically in the file:
numpy/core/code_generators/generate_ufunc_api.py

The following line 54(?) should have be removed.
Py_DECREF(numpy);

numpy-gitbot · 2012-10-23T02:43:07Z

Attachment added by @bsouthey on 2010-03-10: generate_ufunc_api.diff

numpy-gitbot · 2012-10-23T02:43:07Z

@pv wrote on 2010-03-10

Nice sleuthing!

But things don't seem very straightforward at all here: the refcounting there in itself seems perfectly solid. Before fixing this, the reason for the failure should preferably be better understood, and explained as a comment in the code.

The issue seems to be something like this: when Python exits, it deallocates stuff. However, the numpy module is deallocated before some stuff that tries to use after deallocation -> bomb.

It might be a hint that the failure occurs only in umath_tests -- maybe there's something amiss there?

numpy-gitbot · 2012-10-23T02:43:07Z

numpy-gitbot commented

Oct 23, 2012

@pv

Milestone changed to NumPy 2.0 by @pv on 2010-03-10

numpy-gitbot · 2012-10-23T02:43:08Z

@bsouthey wrote on 2010-03-10

It was an interesting and learning experience even if it was 99.99% trial and error! From the very little I understand, this defines the umath and ufunc APIs so it should occur with those tests.

Looking further, the line might just be out of place. When I look at the '#if PY_VERSION_HEX >= 0x03010000', I see two Py_DECREF(c_api); statements but only one 'Py_DECREF(numpy);' statement.

numpy-gitbot · 2012-10-23T02:43:08Z

@charris wrote on 2010-05-25

Pauli, I believe you fixed this in r8408.

numpy-gitbot · 2012-10-23T02:43:08Z

@charris wrote on 2010-05-25

I don't see this crash in recent svn, so I am closing the ticket. If there is still a problem reopen it.

numpy-gitbot · 2012-10-23T02:43:10Z

Milestone changed to 1.6.0 by @mwiebe on 2011-05-24

thouis closed this as completed Oct 19, 2012

seberg mentioned this issue Oct 30, 2021

Added new Dummy function #20218

Closed

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importing umath_tests and then CTRL-D crashes with core dump (Trac #1425) #2023

importing umath_tests and then CTRL-D crashes with core dump (Trac #1425) #2023

importing umath_tests and then CTRL-D crashes with core dump (Trac #1425) #2023

importing umath_tests and then CTRL-D crashes with core dump (Trac #1425) #2023

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