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tkinter: avoid reference loops with Variables and Fonts #66266

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serhiy-storchaka opened this issue Jul 25, 2014 · 12 comments
Closed

tkinter: avoid reference loops with Variables and Fonts #66266

serhiy-storchaka opened this issue Jul 25, 2014 · 12 comments
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@serhiy-storchaka
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topic-tkinter type-bug An unexpected behavior, bug, or error

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@serhiy-storchaka
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BPO 22068
Nosy @terryjreedy, @kbkaiser, @vstinner, @serwy, @serhiy-storchaka
Files
  • tracemalloc.txt
  • regrtest_tracemalloc.patch
  • tkinter_refloops-2.7.patch
    		•

    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/serhiy-storchaka'
closed_at = <Date 2014-08-17.13:47:14.536>
created_at = <Date 2014-07-25.15:34:59.628>
labels = ['type-bug', 'expert-tkinter']
title = 'tkinter: avoid reference loops with Variables and Fonts'
updated_at = <Date 2014-08-17.13:47:14.536>
user = 'https://github.com/serhiy-storchaka'

    bugs.python.org fields:

    activity = <Date 2014-08-17.13:47:14.536>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2014-08-17.13:47:14.536>
closer = 'serhiy.storchaka'
components = ['Tkinter']
creation = <Date 2014-07-25.15:34:59.628>
creator = 'serhiy.storchaka'
dependencies = []
files = ['36087', '36088', '36105']
hgrepos = []
issue_num = 22068
keywords = ['patch']
message_count = 12.0
messages = ['223958', '223960', '223961', '223963', '224021', '224033', '224042', '224092', '224361', '224363', '225273', '225440']
nosy_count = 6.0
nosy_names = ['terry.reedy', 'kbk', 'vstinner', 'roger.serwy', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue22068'
versions = ['Python 2.7', 'Python 3.4', 'Python 3.5']
    @serhiy-storchaka
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    $ ./python -m test.regrtest -ugui -v test_idle test_gc
...

    ======================================================================
    FAIL: test_saveall (test.test_gc.GCTests)
    ----------------------------------------------------------------------

    Traceback (most recent call last):
  File "/home/serhiy/py/cpython-2.7/Lib/test/test_gc.py", line 200, in test_saveall
    self.assertEqual(gc.garbage, [])
AssertionError: Lists differ: [<Tkinter.StringVar instance a... != []

    First list contains 24 additional elements.
    First extra element 0:
    PY_VAR0

    Diff is 1123 characters long. Set self.maxDiff to None to see it.

    ----------------------------------------------------------------------

    @serhiy-storchaka serhiy-storchaka added topic-IDLE tests Tests in the Lib/test dir type-bug An unexpected behavior, bug, or error labels Jul 25, 2014
    @vstinner
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    It looks like test_idle leaks uncollectable objects.

    I modified regrtest to use tracemalloc, I attach the output: tracemalloc.txt. Good luck to find the leaks ;-)

    @vstinner
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    regrtest_tracemalloc.patch: my patch for regrtest.py to dump the traceback where garbage objects where allocated using tracemalloc.
    http://pytracemalloc.readthedocs.org/

    (Note: you need to recompile Python to use tracemalloc on Python < 3.4.)

    @serhiy-storchaka
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    Indeed, there are a lot of small reference loops in ConfigDialog. Tk variables save reference to the dialog and the dialog saves references to variables. Either variables should be created with different argument (i.e. self.parent), or they should be deleted when ConfigDialog is destroyed.

    @terryjreedy
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    ConfigDialog is a good guess as I added a minimal test this month.
    I will try to revise to not create loops in the first place.

    @serhiy-storchaka
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    Here is a patch against 2.7 which get rid of reference loops in Tk variables and Font. This will fix not only ConfigDialog, but any similar user code.

    In 3.4+ such reference loops are successfully resolved, but I think we should foreport this path to 3.4+ because it also fixes other minor bug: callbacks registered to trace variable now live while the variable lives, not while widget lives.

    @serhiy-storchaka serhiy-storchaka self-assigned this Jul 26, 2014
    @vstinner
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    I agree that the patch shoukd also br applied to 3.4.

    @terryjreedy
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    F:\Python\dev>2\py27\pcbuild\python_d.exe -m test.regrtest -R :: -uall test_idle
    test_idle leaked [1945, 1945, 1945, 1945] references, sum=7780

    There are none with 3.4, so the new gc is doing its job.
    There are also none with test_configdialog renamed xtest... ,

    GetCfgSectionNameDialog.__init__ in configSectionNameDialog.py saves self.parent for later use as the parent for XyxVars. I am looking at doing the same for config dialog.

    @vstinner vstinner changed the title test_gc fails after test_idle test_idle leaks uncollectable objects Jul 29, 2014
    @python-dev
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    python-dev mannequin commented Jul 30, 2014

    New changeset 6b7f189daa62 by Terry Jan Reedy in branch '2.7':
    Issue bpo-22068: Don't create self reference cycles in idlelib.ConfigDialog.
    http://hg.python.org/cpython/rev/6b7f189daa62

    New changeset 1927f47a1838 by Terry Jan Reedy in branch '3.4':
    Issue bpo-22068: Don't create self reference cycles in idlelib.ConfigDialog.
    http://hg.python.org/cpython/rev/1927f47a1838

    @terryjreedy
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    -R no longer finds leaks with current Idle tests. There might still be some in modules not tested.

    @terryjreedy terryjreedy removed topic-IDLE tests Tests in the Lib/test dir labels Jul 30, 2014
    @terryjreedy terryjreedy changed the title test_idle leaks uncollectable objects tkinter: avoid reference loops with Variables and Fonts Jul 30, 2014
    @serhiy-storchaka
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    If there are no objections I'll commit the patch.

    @python-dev
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    python-dev mannequin commented Aug 17, 2014

    New changeset 0b79c702abda by Serhiy Storchaka in branch '2.7':
    Issue bpo-22068: Avoided reference loops with Variables and Fonts in Tkinter.
    http://hg.python.org/cpython/rev/0b79c702abda

    New changeset 873002eb8087 by Serhiy Storchaka in branch '3.4':
    Issue bpo-22068: Avoided reference loops with Variables and Fonts in Tkinter.
    http://hg.python.org/cpython/rev/873002eb8087

    New changeset f44f5daff665 by Serhiy Storchaka in branch 'default':
    Issue bpo-22068: Avoided reference loops with Variables and Fonts in Tkinter.
    http://hg.python.org/cpython/rev/f44f5daff665

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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