Python 2.7 crashes in Linux environment

[HuyK]

BPO	30478
Nosy	@ncoghlan, @mlouielu
Files	python_crashes.png: Captured picture about coredump message weather_station.py: Python application

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2017-05-26.02:52:54.074>
created_at = <Date 2017-05-26.01:48:32.322>
labels = ['interpreter-core', 'type-crash']
title = 'Python 2.7 crashes in Linux environment'
updated_at = <Date 2017-05-26.02:52:54.061>
user = 'https://bugs.python.org/HuyK'

bugs.python.org fields:

activity = <Date 2017-05-26.02:52:54.061>
actor = 'ncoghlan'
assignee = 'none'
closed = True
closed_date = <Date 2017-05-26.02:52:54.074>
closer = 'ncoghlan'
components = ['Interpreter Core']
creation = <Date 2017-05-26.01:48:32.322>
creator = 'HuyK'
dependencies = []
files = ['46903', '46904']
hgrepos = []
issue_num = 30478
keywords = []
message_count = 4.0
messages = ['294520', '294525', '294527', '294528']
nosy_count = 3.0
nosy_names = ['ncoghlan', 'louielu', 'HuyK']
pr_nums = []
priority = 'normal'
resolution = 'third party'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue30478'
versions = ['Python 2.7']

[HuyK]

Hi all,

I have a python script to run as a Weather Station application. The python script runs on Raspberry Pi 3 board. It gets weather data from OpenWeatherMap website and sends result to a remote touch-screen device via COM port to display

It uses two main libraries to handle the task:
https://pypi.python.org/pypi/ftd2xx
https://github.com/csparpa/pyowm

I got the python script just exits without any error after sometimes. Checking the return code with the command "echo $?" in Pi's console window and got 139 which means a Segmentation Fault

We tried to generate coredump system when the python script crashes and we got this:
"Core was generated by 'python weather_station.py'
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0005b614 in complex_subtype_from_string (type=0x746150, v=0x72616843) at ../Objects/complexobject.c:1075"

I tried to update to Python 2.7.13 but the crashes still happens.

My question is if the segmentation fault related to complexobject.c has been reported and fixed?

Best regards,
HuyK

[mlouielu]

Hi Huyk, which version of Python does the error message generated?

Also, could you try to provide a minimum reproduce python script and upload it? it will be more easy to debug this problem if we can reproduce this.

[HuyK]

Hi Louie Lu,

You will need a touch-screen device running corresponding firmware in order to run the python application. FYI, I tried to run only weather data fetching or only COM port communication but the crash did not happen. It happens when I run both tasks.
Anyway, I attach the python script for your reference.
First, I got the issue with 2.7.9. And after updating to 2.7.13, I still get the crash issue

Thanks,
HuyK

[ncoghlan]

Hi HuyK, thanks for the issue report, and in particular the pointers to the key external libraries the script uses.

It seems ftd2xx relies on ctypes to wrap an external library, which means that this report falls under the general policy of "triggering a segfault with ctypes is assumed to be a bug in the usage of ctypes, rather than a bug in ctypes itself".

If you'd like to investigate further before filing a bug report with the ftd2xx authors, you may want to try out the Python 2.7 backport of Python 3's faulthandler library: https://faulthandler.readthedocs.io/

That should be able to give you a Python traceback at the point where the segfault occurs, rather than trying to reverse engineer that information from the core dump.