Bug report
Bug description:
The threading module defines local as follows:
|
try: |
|
from _thread import _local as local |
|
except ImportError: |
|
from _threading_local import local |
But _threading_local also uses threading as follows:
|
from threading import current_thread, RLock |
This was fine at first, since threading never used thread-local data (the import was near the end). However, this changed in gh-114424:
|
# Helper thread-local instance to detect when a _DummyThread |
|
# is collected. Not a part of the public API. |
|
_thread_local_info = local() |
The _threading_local.local object depends on threading.current_thread(), and this dependency occurs when the object is created:
|
# We need to create the thread dict in anticipation of |
|
# __init__ being called, to make sure we don't call it |
|
# again ourselves. |
|
impl.create_dict() |
|
def create_dict(self): |
|
"""Create a new dict for the current thread, and return it.""" |
|
localdict = {} |
|
key = self.key |
|
thread = current_thread() |
The object is created (and local is imported) before current_thread() is defined. As a result, there is the broken circular import, which can be reproduced as follows:
>>> import _thread
>>> del _thread._local
>>> import threading
Traceback (most recent call last):
File "/home/user/.local/share/mise/installs/python/3.14.7/lib/python3.14/threading.py", line 67, in <module>
from _thread import _local as local
ImportError: cannot import name '_local' from '_thread' (unknown location)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "<python-input-2>", line 1, in <module>
import threading
File "/home/user/.local/share/mise/installs/python/3.14.7/lib/python3.14/threading.py", line 69, in <module>
from _threading_local import local
File "/home/user/.local/share/mise/installs/python/3.14.7/lib/python3.14/_threading_local.py", line 120, in <module>
from threading import current_thread, RLock
ImportError: cannot import name 'current_thread' from partially initialized module 'threading' (most likely due to a circular import) (/home/user/.local/share/mise/installs/python/3.14.7/lib/python3.14/threading.py)Since the issue has not been reported before, this raises a legitimate question: is the fallback still relevant?
Related: #141460.
CPython versions tested on:
3.13, 3.14
Operating systems tested on:
Linux
Bug report
Bug description:
The
threadingmodule defineslocalas follows:cpython/Lib/threading.py
Lines 67 to 70 in ee521e8
But
_threading_localalso usesthreadingas follows:cpython/Lib/_threading_local.py
Line 120 in ee521e8
This was fine at first, since
threadingnever used thread-local data (the import was near the end). However, this changed in gh-114424:cpython/Lib/threading.py
Lines 1540 to 1542 in ee521e8
The
_threading_local.localobject depends onthreading.current_thread(), and this dependency occurs when the object is created:cpython/Lib/_threading_local.py
Lines 93 to 96 in ee521e8
cpython/Lib/_threading_local.py
Lines 42 to 46 in ee521e8
The object is created (and
localis imported) beforecurrent_thread()is defined. As a result, there is the broken circular import, which can be reproduced as follows:Since the issue has not been reported before, this raises a legitimate question: is the fallback still relevant?
Related: #141460.
CPython versions tested on:
3.13, 3.14
Operating systems tested on:
Linux