pytest segfault, not with -v

[Barry]

> On 18 Dec 2021, at 20:05, Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
> 
> Emh, maybe I was not clear. I created a C extension and it segfaults.
> So I created that script to see where it segfaults. But the script
> does not segfault. My doubt is: is that because I'm using eval and
> exec in the script?

You may struggle to duplicate the pattern of memory allocations and accesses that lead to the segv.

Assuming you are on a unix, turn on coredumps and run the code until it segfaults.
Then use gdb on the core file.

Barry

> 
>> On Sat, 18 Dec 2021 at 18:33, Dieter Maurer <dieter at handshake.de> wrote:
>> 
>> Marco Sulla wrote at 2021-12-18 14:10 +0100:
>>> Ok, I created the script:
>>> 
>>> https://github.com/Marco-Sulla/python-frozendict/blob/master/test/debug.py
>>> 
>>> The problem is it does _not_ crash, while a get a segfault using
>>> pytest with python 3.9 on MacOS 10.15
>>> 
>>> Maybe it's because I'm using eval / exec in the script?
>> 
>> Segfaults can result from C stack overflow which in turn can
>> be caused in special cases by too deeply nested function calls
>> (usually, Python's "maximal recursion depth exceeded" prevents
>> this before a C stack overflow).
>> 
>> Otherwise, whatever you do in Python (this includes "eval/exec")
>> should not cause a segfault. The cause for it likely comes from
>> a memory management bug in some C implemented part of your
>> application.
>> 
>> Note that memory management bugs may not show deterministic
>> behavior. Minor changes (such as "with/without -v")
>> can significantly change the outcome.
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