◐ Shell
reader mode source ↗
Skip to content

bpo-44263: Better explain the GC contract for PyType_FromSpecWithBases#26442

Merged
pablogsal merged 1 commit into
python:mainfrom
pablogsal:gc_docs
May 29, 2021
Merged

bpo-44263: Better explain the GC contract for PyType_FromSpecWithBases#26442
pablogsal merged 1 commit into
python:mainfrom
pablogsal:gc_docs

Conversation

@pablogsal

@pablogsal pablogsal commented May 29, 2021 •
edited by bedevere-bot
Loading

Copy link
Copy Markdown
Member

@bedevere-bot bedevere-bot added awaiting core review docs Documentation in the Doc dir labels May 29, 2021
@pablogsal pablogsal requested review from encukou and vstinner and removed request for encukou May 29, 2021 00:01
@pablogsal

pablogsal commented May 29, 2021

Copy link
Copy Markdown
Member Author

CC: @erlend-aasland

Fidget-Spinner
Fidget-Spinner approved these changes May 29, 2021
View reviewed changes

@Fidget-Spinner Fidget-Spinner left a comment

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Hide comment

Thanks for the clarifications. I was pretty confused with your fix at 8b4312b. So I'm glad the reason is in the docs now!

If I'm understanding correctly, in that specific case, you want _ssl.SSLError to inherit its tp_traverse etc. fields from the parent PyExc_OSError (which implements the GC), so you didn't set Py_TPFLAGS_HAVE_GC in _ssl.SSLError?

@pablogsal

pablogsal commented May 29, 2021

Copy link
Copy Markdown
Member Author

If I'm understanding correctly, in that specific case, you want _ssl.SSLError to inherit its tp_traverse etc. fields from the parent PyExc_OSError (which implements the GC), so you didn't set Py_TPFLAGS_HAVE_GC in _ssl.SSLError?

Correct, this is because SSLError doesn't add any extra fields: is just PyOSErrorObject.

@pablogsal pablogsal merged commit 8b55bc3 into python:main May 29, 2021
@pablogsal pablogsal deleted the gc_docs branch May 29, 2021 02:57
@miss-islington

miss-islington commented May 29, 2021

Copy link
Copy Markdown
Contributor

Thanks @pablogsal for the PR 🌮🎉.. I'm working now to backport this PR to: 3.10, 3.9.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

@bedevere-bot

bedevere-bot commented May 29, 2021

Copy link
Copy Markdown

GH-26443 is a backport of this pull request to the 3.10 branch.

@bedevere-bot bedevere-bot removed the needs backport to 3.10 only security fixes label May 29, 2021
@bedevere-bot

bedevere-bot commented May 29, 2021

Copy link
Copy Markdown

GH-26444 is a backport of this pull request to the 3.9 branch.

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request May 29, 2021
@pablogsal @miss-islington
bpo-44263: Better explain the GC contract for PyType_FromSpecWithBases ( …
0974c96 
pythonGH-26442)

(cherry picked from commit 8b55bc3)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
miss-islington added a commit that referenced this pull request May 29, 2021
@miss-islington @pablogsal
bpo-44263: Better explain the GC contract for PyType_FromSpecWithBases ( …
a30cbae 
GH-26442)

(cherry picked from commit 8b55bc3)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
pablogsal added a commit that referenced this pull request May 29, 2021
@miss-islington @pablogsal
bpo-44263: Better explain the GC contract for PyType_FromSpecWithBases ( …
11049be 
GH-26442) (GH-26443)

(cherry picked from commit 8b55bc3)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
@encukou

encukou commented Jun 1, 2021

Copy link
Copy Markdown
Member

Thank you for the clarification!

@vstinner

vstinner commented Jun 1, 2021

Copy link
Copy Markdown
Member

Thank you for the clarification!

Yeah, thanks Pablo! This part wasn't obvious to me at all, especially the type inheritance part.

FYI Pablo and me hit this issue the hard way while debugging a random crash involving the _ssl.SSLError exception: https://bugs.python.org/issue44252 Two unit tests only crashed on Windows, and only if you ran the unit test in a very specific way. GC collections are not really "determistic" from my human debugger pointer of view :-) I made the crash more likely by running import gc; gc.set_threshold(5) at Python startup.

@pablogsal pablogsal mentioned this pull request Jul 18, 2021
Closed
@pablogsal pablogsal mentioned this pull request May 2, 2022
Closed
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@Fidget-Spinner Fidget-Spinner Fidget-Spinner approved these changes

@vstinner vstinner Awaiting requested review from vstinner

@encukou encukou Awaiting requested review from encukou

Assignees

No one assigned

Labels

docs Documentation in the Doc dir skip news

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

7 participants

@pablogsal @miss-islington @bedevere-bot @encukou @vstinner @Fidget-Spinner @the-knights-who-say-ni