Better repr for threading.Lock()

[rhettinger]

BPO	21137
Nosy	@rhettinger, @pitrou, @berkerpeksag, @serhiy-storchaka
Files	issue21137.diff issue21137_v2.diff issue21137_v3.diff

^{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 = 'https://github.com/rhettinger'
closed_at = <Date 2014-05-26.01:23:20.591>
created_at = <Date 2014-04-03.01:19:02.742>
labels = ['easy', 'type-feature', 'library']
title = 'Better repr for threading.Lock()'
updated_at = <Date 2014-05-26.05:21:13.380>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2014-05-26.05:21:13.380>
actor = 'berker.peksag'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2014-05-26.01:23:20.591>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2014-04-03.01:19:02.742>
creator = 'rhettinger'
dependencies = []
files = ['34710', '35118', '35321']
hgrepos = []
issue_num = 21137
keywords = ['patch', 'easy']
message_count = 10.0
messages = ['215413', '215416', '215436', '215437', '217440', '217637', '218940', '218942', '219116', '219117']
nosy_count = 5.0
nosy_names = ['rhettinger', 'pitrou', 'python-dev', 'berker.peksag', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue21137'
versions = ['Python 3.5']

[rhettinger]

It is really nice to have the open/closed status in the __repr__ of file objects:

<open file 'data.txt', mode 'r' at 0x102c8ec90>
<closed file 'data.txt', mode 'r' at 0x102c8ec90>

I would like to have the same for locks:

<unlocked thread.lock object at 0x1002b1330>
<locked thread.lock object at 0x1002b1330>

This would be nice in logs and tracebacks for example.

[berkerpeksag]

Here's a patch with a test. Example repr of threading.Lock():

    $ ./python -c "import threading; print(threading.Lock())"
    <unlocked _thread.lock object>

[serhiy-storchaka]

The repr of threading._RLock contains owner and count, but not lock/unlock status. The repr of locks from _dummy_thread also should contain lock/unlock status. And it would be nice to have the open/closed status in the repr of other synchronization primitives: Condition, Semaphore, etc.

As for tests, I think assertRegex() will produce more useful error report.

[serhiy-storchaka]

And of course we should keep "at 0x..." part, because it is the way to distinguish different lock objects.

[pitrou]

The repr of threading._RLock contains owner and count, but not
lock/unlock status. The repr of locks from _dummy_thread also should
contain lock/unlock status. And it would be nice to have the
open/closed status in the repr of other synchronization primitives:
Condition, Semaphore, etc.

I think it's ok to stay focussed and restrict this issue to threading.Lock (and perhaps RLock).

Berker, do you want to provide an updated patch?

[berkerpeksag]

Here's an updated patch. Thanks for the reviews.

And of course we should keep "at 0x..." part, because it is the way to distinguish different lock objects.

Done.

    $ ./python -c "import threading; l = threading.Lock(); print(l)"
    <unlocked _thread.lock object at 0x7f0a19e7b1f8>

The repr of threading._RLock contains owner and count, but not lock/unlock status.

Done.

    $ ./python -c "import threading; rl = threading.RLock(); rl.acquire(); print(rl)"
    <locked _thread.RLock object owner=139769600231168 count=1>

The repr of locks from _dummy_thread also should contain lock/unlock status.

Done.

    $ ./python -c "import dummy_threading as threading; l = threading.Lock(); print(l)"
    <unlocked _dummy_thread.LockType object at 0x7fb334245400>

    $ ./python -c "import dummy_threading as threading; l = threading.RLock(); print(l)"
    <unlocked threading._RLock object owner=None count=0 at 0x7f524d0138e0>

As for tests, I think assertRegex() will produce more useful error report.

Done.

[rhettinger]

The patch is just about ready to go but needs to address some failing tests:

======================================================================
FAIL: test_locked_repr (test.test_importlib.test_locks.Frozen_ModuleLockAsRLockTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/Users/raymond/cpython/Lib/test/lock_tests.py", line 91, in test_locked_repr
    self.assertRegex(repr(lock), "<locked .* object (.*)?at .*>")
AssertionError: Regex didn't match: '<locked .* object (.*)?at .*>' not found in "_ModuleLock('some_lock') at 4438138048"

======================================================================
FAIL: test_repr (test.test_importlib.test_locks.Frozen_ModuleLockAsRLockTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/Users/raymond/cpython/Lib/test/lock_tests.py", line 85, in test_repr
    self.assertRegex(repr(lock), "<unlocked .* object (.*)?at .*>")
AssertionError: Regex didn't match: '<unlocked .* object (.*)?at .*>' not found in "_ModuleLock('some_lock') at 4439151784"

======================================================================
FAIL: test_locked_repr (test.test_importlib.test_locks.Source_ModuleLockAsRLockTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/Users/raymond/cpython/Lib/test/lock_tests.py", line 91, in test_locked_repr
    self.assertRegex(repr(lock), "<locked .* object (.*)?at .*>")
AssertionError: Regex didn't match: '<locked .* object (.*)?at .*>' not found in "_ModuleLock('some_lock') at 4438192312"

======================================================================
FAIL: test_repr (test.test_importlib.test_locks.Source_ModuleLockAsRLockTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/Users/raymond/cpython/Lib/test/lock_tests.py", line 85, in test_repr
    self.assertRegex(repr(lock), "<unlocked .* object (.*)?at .*>")
AssertionError: Regex didn't match: '<unlocked .* object (.*)?at .*>' not found in "_ModuleLock('some_lock') at 4438192480"

---

Ran 970 tests in 0.549s

FAILED (failures=4, skipped=7, expected failures=1)
test test_importlib failed
1 test failed:
test_importlib

[berkerpeksag]

Here is a new patch. I've disabled test_repr and test_locked_repr tests in Lib/test/test_importlib/test_locks.py.

[python-dev]

New changeset 7574f94b1068 by Raymond Hettinger in branch 'default':
bpo-21137: Better repr for threading.Lock()
http://hg.python.org/cpython/rev/7574f94b1068

[rhettinger]

Thanks Berker.