homebrew: docbuild crashes, libtcl AtForkPrepare - from sage.misc.cython globals / multiprocessing

[mkoeppe]

(from #31335, reported in https://groups.google.com/g/sage-devel/c/9EMs9h2i_H4)

CC: @jhpalmieri @zlscherr @kiwifb @kliem

Component: build

Author: Matthias Koeppe, John Palmieri

Branch/Commit: b4ceee5

Reviewer: John Palmieri

Issue created by migration from https://trac.sagemath.org/ticket/31344

[mkoeppe]

comment:1

Bisecting src/doc/en/reference/misc/index.rst (running ./sage -docbuild --keep-going all html) reveals that the crash is coming from sage.misc.cython

[mkoeppe]

comment:2

For some reason, this line: cblas_pc = pkgconfig.parse(get_cblas_pc_module_name())
seems to cause the trouble.

[mkoeppe]

Branch: u/mkoeppe/homebrew__docbuild_crashes__libtcl_atforkprepare

[mkoeppe]

New commits:

80720d7

src/sage/misc/cython.py: Do not run pkgconfig at import time

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: 80720d7

[mkoeppe]

comment:5

Easiest to test on #31335, which merges this branch

[jhpalmieri]

comment:6

With #31335, I still see a failure during docbuilding when using homebrew's Python with Big Sur. The failure now appears when building thematic_tutorials instead of the reference manual.

------------------------------------------------------------------------
0   signals.cpython-39-darwin.so        0x00000001047e2542 print_backtrace + 66
1   signals.cpython-39-darwin.so        0x00000001047e6167 sigdie + 39
2   signals.cpython-39-darwin.so        0x00000001047e606a cysigs_signal_handler + 282
3   libsystem_platform.dylib            0x00007fff20486d7d _sigtramp + 29
4   Python                              0x00000001029edcf1 _PyArg_ParseTuple_SizeT + 158
5   libtcl8.6.dylib                     0x000000034143972e AtForkPrepare + 38
6   libsystem_pthread.dylib             0x00007fff204421a3 _pthread_atfork_prepare_handlers + 90
7   libSystem.B.dylib                   0x00007fff2a645934 libSystem_atfork_prepare + 11
8   libsystem_c.dylib                   0x00007fff20325b1b fork + 12
9   _posixsubprocess.cpython-39-darwin. 0x00000001030d77f3 subprocess_fork_exec + 860
10  Python                              0x000000010291c2da cfunction_call + 90
11  Python                              0x00000001028d1b56 _PyObject_MakeTpCall + 129
12  Python                              0x00000001029ca625 call_function + 278
13  Python                              0x00000001029c7e86 _PyEval_EvalFrameDefault + 45416
14  Python                              0x00000001029bbbd6 _PyEval_EvalCode + 403
...
272 Python                              0x00000001028d2774 _PyFunction_Vectorcall + 376
273 Python                              0x0000000102a3ade0 pymain_run_module + 212
274 Python                              0x0000000102a3a8aa pymain_run_python + 433
275 Python                              0x0000000102a3a6bd Py_RunMain + 23
276 Python                              0x0000000102a3b9da pymain_main + 35
277 Python                              0x0000000102a3bcb0 Py_BytesMain + 42
278 libdyld.dylib                       0x00007fff2045d621 start + 1
------------------------------------------------------------------------
Unhandled SIGILL: An illegal instruction occurred.
This probably occurred because a *compiled* module has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Python will now terminate.
------------------------------------------------------------------------

[mkoeppe]

comment:7

Thanks for testing! I'll try a clean rebuild of the documentation and see if I can reproduce it on Catalina as well.

For reference, the trick for bisecting was to use

make build && ./sage -docbuild --keep-going all html ; ./sage -docbuild all html

the first --keep-going was necessary so that WARNING: document isn't included in any toctree does not stop the whole process.

[mkoeppe]

comment:8

OK, I can reproduce it

[mkoeppe]

comment:9

reducing thematic_tutorials/index.rst to the following still reproduces the crash:

.. Sage documentation master file, created by sphinx-quickstart on Thu
.. Aug 21 20:15:55 2008. You can adapt this file completely to your
.. liking, but it should at least contain the root `toctree` directive.

.. _thematic-tutorials:

Welcome to the Sage Thematic Tutorials!
=======================================


* `Tutorial: Symbolics and Plotting (PREP) <../prep/Symbolics-and-Basic-Plotting.html>`_

[mkoeppe]

comment:10

That's in an incremental docbuild - so something bad must have been saved in the inventory.

[jhpalmieri]

comment:11

When I saw the original problem, I only saw it on the second pass through the ref manual build, which is consistent with seeing problems based on something in the inventory.

[zlscherr]

comment:12

Does anyone know why

./sage --docbuild all html

fails at thematic_tutorial but

./sage --docbuild thematic_tutorial html

works?

[zlscherr]

comment:13

In fact, after

./sage -docbuild --keep-going all html

failed, I tried building thematic_tutorial by itself. That worked, and then make doc says it was successful.