Memory leak in comparison of sqlite.Row objects

[serhiy-storchaka]

BPO	38175
Nosy	@berkerpeksag, @serhiy-storchaka, @miss-islington
PRs	bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. #16155 [3.8] bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155) #16193 [3.7] bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155) #16194 [2.7] bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155). #16215

^{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 2019-09-17.06:56:48.525>
created_at = <Date 2019-09-15.07:29:06.991>
labels = ['3.8', '3.7', 'library', '3.9', 'performance']
title = 'Memory leak in comparison of sqlite.Row objects'
updated_at = <Date 2019-09-17.06:56:48.524>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2019-09-17.06:56:48.524>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2019-09-17.06:56:48.525>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2019-09-15.07:29:06.991>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 38175
keywords = ['patch']
message_count = 5.0
messages = ['352465', '352558', '352601', '352602', '352614']
nosy_count = 4.0
nosy_names = ['ghaering', 'berker.peksag', 'serhiy.storchaka', 'miss-islington']
pr_nums = ['16155', '16193', '16194', '16215']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue38175'
versions = ['Python 2.7', 'Python 3.7', 'Python 3.8', 'Python 3.9']

[serhiy-storchaka]

There is a memory leak in comparison of sqlite.Row objects when row descriptors are different. There were not tests for this case.

Also, the code compares the result of PyObject_RichCompare() with Py_True and Py_False. It is better to avoid such code, because technically PyObject_RichCompare() can return an arbitrary value, although in this particular case description can only be tuple or None (or NULL, but this is other issue).

Also, there is a test for inequality of hash codes. Since hashes depend on hashes of strings, they value is random, and there is a small chance of failure. Hashes should not be tested for inequality.

[serhiy-storchaka]

New changeset 8debfa5 by Serhiy Storchaka in branch 'master':
bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155)
8debfa5

[miss-islington]

New changeset f04299d by Miss Islington (bot) in branch '3.8':
bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155)
f04299d

[miss-islington]

New changeset 4ac1be2 by Miss Islington (bot) in branch '3.7':
bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155)
4ac1be2

[serhiy-storchaka]

New changeset be257bc by Serhiy Storchaka in branch '2.7':
[2.7] bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects. (GH-16155). (GH-16215)
be257bc