Memory leak in Tkinter

[dtalkin]

BPO	34794
Nosy	@vstinner, @serhiy-storchaka, @miss-islington, @tirkarthi
PRs	[2.7] bpo-34794: Fix a memory leak in Tkinter.Image. #9559 bpo-34794: Fix a leak in Tkinter. #10025 [3.7] bpo-34794: Fix a leak in Tkinter. (GH-10025) #10069 [3.6] bpo-34794: Fix a leak in Tkinter. (GH-10025) #10070 [2.7] bpo-34794: Fix a leak in Tkinter. (GH-10025) #10181
Files	leak_demo.py leak_demo2.py

^{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 2018-10-28.19:14:46.622>
created_at = <Date 2018-09-24.21:30:12.174>
labels = ['3.8', '3.7', 'expert-tkinter', 'performance']
title = 'Memory leak in Tkinter'
updated_at = <Date 2018-10-28.19:14:46.621>
user = 'https://bugs.python.org/dtalkin'

bugs.python.org fields:

activity = <Date 2018-10-28.19:14:46.621>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2018-10-28.19:14:46.622>
closer = 'serhiy.storchaka'
components = ['Tkinter']
creation = <Date 2018-09-24.21:30:12.174>
creator = 'dtalkin'
dependencies = []
files = ['47821', '47886']
hgrepos = []
issue_num = 34794
keywords = ['patch']
message_count = 8.0
messages = ['326289', '326327', '326355', '328205', '328338', '328342', '328347', '328715']
nosy_count = 5.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'miss-islington', 'xtreak', 'dtalkin']
pr_nums = ['9559', '10025', '10069', '10070', '10181']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue34794'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7', 'Python 3.8']

[dtalkin]

The Tkinter.PhotoImage class leaks memory with each change of the 'data' Attribute due to Image calling tk._createbytearray, which allocates memory, but never frees it.

The offending method is in the TkApp class, _createbytearray().

[tirkarthi]

Thanks for the report David. Feel free to attach reproducible script if any that might trigger this. I am adding Serhiy who might have a better understanding of this. Relevant issue where _createbytearray was added : bpo-21580 .

[dtalkin]

Attached please find a Python script that demonstrates the bug.

David

On Tue, Sep 25, 2018 at 2:55 AM Karthikeyan Singaravelan <
report@bugs.python.org> wrote:

Karthikeyan Singaravelan <tir.karthi@gmail.com> added the comment:

Thanks for the report David. Feel free to attach reproducible script if
any that might trigger this. I am adding Serhiy who might have a better
understanding of this. Relevant issue where _createbytearray was added :
bpo-21580 .

----------
nosy: +serhiy.storchaka, xtreak

---

Python tracker <report@bugs.python.org>
<https://bugs.python.org/issue34794\>

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[serhiy-storchaka]

Here is a simpler reproducer.

Actually the problem was not in _createbytearray(), but in converting the Python wrapper around Tcl_Obj into Tcl_Obj. _createbytearray() just exposed it. The leak exists in Python 3 too, but it is hard to reproduce it.

[serhiy-storchaka]

New changeset df13df4 by Serhiy Storchaka in branch 'master':
bpo-34794: Fix a leak in Tkinter. (GH-10025)
df13df4

[miss-islington]

New changeset 2c54925 by Miss Islington (bot) in branch '3.6':
bpo-34794: Fix a leak in Tkinter. (GH-10025)
2c54925

[vstinner]

New changeset f7cefb4 by Victor Stinner (Miss Islington (bot)) in branch '3.7':
bpo-34794: Fix a leak in Tkinter. (GH-10025) (GH-10069)
f7cefb4

[serhiy-storchaka]

New changeset aaea280 by Serhiy Storchaka in branch '2.7':
[2.7] bpo-34794: Fix a leak in Tkinter. (GH-10025) (GH-10181)
aaea280