test_io is leaking references

[pablogsal]

BPO	42145
Nosy	@pablogsal, @shihai1991

^{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 2020-10-25.18:39:32.963>
created_at = <Date 2020-10-25.05:51:18.166>
labels = ['tests', '3.10']
title = 'test_io is leaking references'
updated_at = <Date 2020-10-25.18:39:50.596>
user = 'https://github.com/pablogsal'

bugs.python.org fields:

activity = <Date 2020-10-25.18:39:50.596>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2020-10-25.18:39:32.963>
closer = 'pablogsal'
components = ['Tests']
creation = <Date 2020-10-25.05:51:18.166>
creator = 'pablogsal'
dependencies = []
files = []
hgrepos = []
issue_num = 42145
keywords = []
message_count = 5.0
messages = ['379564', '379566', '379591', '379599', '379600']
nosy_count = 2.0
nosy_names = ['pablogsal', 'shihai1991']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue42145'
versions = ['Python 3.10']

[pablogsal]

❯ ./python -m test test_io -m test.test_io.CTextIOWrapperTest.test_read_one_by_one -R :
0:00:00 load avg: 1.59 Run tests sequentially
0:00:00 load avg: 1.59 [1/1] test_io
beginning 9 repetitions
123456789
.........
test_io leaked [3, 3, 3, 3] references, sum=12
test_io leaked [1, 1, 1, 1] memory blocks, sum=4
test_io failed

== Tests result: FAILURE ==

1 test failed:
test_io

Total duration: 398 ms
Tests result: FAILURE

[pablogsal]

Commit c9f696c introduced a reference leak in the test suite. See https://bugs.python.org/issue42145:

c9f696c is the first bad commit
commit c9f696c
Author: Hai Shi <shihai1992@gmail.com>
Date: Fri Oct 16 16:34:15 2020 +0800

bpo-41919, test_codecs: Move codecs.register calls to setUp() (GH-22513)

Reverting the commit eliminates the problem:

rences, sum=12
test_io leaked [1, 1, 1, 1] memory blocks, sum=4
test_io failed

== Tests result: FAILURE ==

1 test failed:
test_io

Total duration: 397 ms
Tests result: FAILURE
g
~/github/python/master master|bisect*
❯ git revert c9f696c
Auto-merging Lib/test/test_codecs.py
[master f3de7c00b4] Revert "bpo-41919, test_codecs: Move codecs.register calls to setUp() (GH-22513)"
7 files changed, 112 insertions(+), 16 deletions(-)

~/github/python/master master|bisect* ⇡
❯ make -j -s
CC='gcc -pthread' LDSHARED='gcc -pthread -shared ' OPT='-g -Og -Wall' _TCLTK_INCLUDES='' _TCLTK_LIBS='' ./python -E ./setup.py -q build

The following modules found by detect_modules() in setup.py, have been
built by the Makefile instead, as configured by the Setup files:
_abc atexit pwd
time

~/github/python/master master|bisect* ⇡
❯ ./python -m test test_io -m test.test_io.CTextIOWrapperTest.test_read_one_by_one -R :
0:00:00 load avg: 2.57 Run tests sequentially
0:00:00 load avg: 2.57 [1/1] test_io
beginning 9 repetitions
123456789
.........

== Tests result: SUCCESS ==

1 test OK.

Total duration: 455 ms
Tests result: SUCCESS

* Move the codecs' (un)register operation to testcases.
* Remove _codecs._forget_codec() and _PyCodec_Forget()

Lib/test/test_charmapcodec.py | 7 +++++--
Lib/test/test_codecs.py | 25 +++----------------------
Lib/test/test_io.py | 7 +++----
Lib/test/test_unicode.py | 5 ++++-
Modules/_codecsmodule.c | 20 --------------------
Modules/clinic/_codecsmodule.c.h | 39 +--------------------------------------
Python/codecs.c | 25 -------------------------
7 files changed, 16 insertions(+), 112 deletions(-)

[shihai1991]

I created a possible fix PR: PR-22973

[pablogsal]

Fixed by #22973

[pablogsal]

Thanks for the quick fix, hai shi