Crash when running SQLAlchemy with pyodbc

[DaveJohansen]

BPO	38665
Nosy	@brettcannon

^{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 2022-01-24.10:51:39.043>
created_at = <Date 2019-11-01.17:56:46.093>
labels = ['3.7', 'type-crash']
title = 'Crash when running SQLAlchemy with pyodbc'
updated_at = <Date 2022-01-24.10:51:39.042>
user = 'https://bugs.python.org/DaveJohansen'

bugs.python.org fields:

activity = <Date 2022-01-24.10:51:39.042>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2022-01-24.10:51:39.043>
closer = 'iritkatriel'
components = []
creation = <Date 2019-11-01.17:56:46.093>
creator = 'Dave Johansen'
dependencies = []
files = []
hgrepos = []
issue_num = 38665
keywords = []
message_count = 4.0
messages = ['355830', '355970', '355972', '355973']
nosy_count = 2.0
nosy_names = ['brett.cannon', 'Dave Johansen']
pr_nums = []
priority = 'normal'
resolution = 'third party'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue38665'
versions = ['Python 3.7']

[DaveJohansen]

We're using SQLAlchemy 1.3.10 with pyodbc 4.0.27 in the python:3.7.5-alpine docker image to connect to a MySQL 13.0.5026.0 database and it's crashing with the following error:
python: malloc.c:2406: sysmalloc: Assertion `(old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize - 1)) == 0)' failed.

[brettcannon]

Can you trace this to actually being Python's fault? Unfortunately you're using two extension modules who both could be at fault with this.

[DaveJohansen]

I can't. I just know that I'm running this process and this crash happens. Any recommendations on how to diagnose that?

[brettcannon]

Basically you have to figure out where that bad memory came from and that's just plain hard in C short of slowly cutting out code until you get a small reproducer. Typically these sorts of issues are almost always in the extension modules, but your case is tricky as even if that's true you don't know which one is the cause.