cell object cleared too early?

[pitrou]

BPO	22164
Nosy	@tim-one, @pitrou

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

Show more details

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2014-08-07.14:32:39.785>
labels = []
title = 'cell object cleared too early?'
updated_at = <Date 2014-08-07.14:32:39.785>
user = 'https://github.com/pitrou'

bugs.python.org fields:

activity = <Date 2014-08-07.14:32:39.785>
actor = 'pitrou'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2014-08-07.14:32:39.785>
creator = 'pitrou'
dependencies = []
files = []
hgrepos = []
issue_num = 22164
keywords = []
message_count = 1.0
messages = ['225012']
nosy_count = 2.0
nosy_names = ['tim.peters', 'pitrou']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue22164'
versions = ['Python 3.4', 'Python 3.5']

[pitrou]

This is a tricky issue I'm sometimes seeing when running Numba's test suite, and I can't seem to write a reproducer. Somtimes I'm seeing the following messages:

Exception ignored in: <function _OverloadedBase._make_finalizer.<locals>.finalizer at 0x7f1466487c80>
Traceback (most recent call last):
  File "/home/antoine/numba/numba/dispatcher.py", line 59, in finalizer
    if shutting_down():
NameError: free variable 'shutting_down' referenced before assignment in enclosing scope

So what does it correspond to? The code is here:
https://github.com/numba/numba/blob/master/numba/dispatcher.py#L47

Basically, there's no way 'shutting_down' can be referenced before assignment... except if it has been cleared. And the only thing which can clear it here is the GC (namely, cell objects' tp_clear() method).

I'm not sure what the exact trigger for reproduction is. It does have to feature a reference cycle involving the closure; perhaps the trashcan mechanism comes into play as well. Also, the closure must be invoked on collection of something in the cycle, so a weakref callback could be nice.

[kumaraditya303]

The issue is 8 years old, has no reproducer and the linked repo does not has dispatcher.py now hence closing. This can be reopened if a reproducer is found or a new issue can be created.