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Created on 2020-11-04 21:56 by Kevin Modzelewski, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Files | ||||
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| File name | Uploaded | Description | Edit | |
| test.py | Kevin Modzelewski, 2020-11-04 21:56 | Test case with unexpected opcache behavior | ||
| Pull Requests | |||
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| URL | Status | Linked | Edit |
| PR 23157 | merged | pablogsal, 2020-11-04 23:12 | |
| Messages (7) | |||
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| msg380370 - (view) | Author: Kevin Modzelewski (Kevin Modzelewski) | Date: 2020-11-04 21:56 | |
The problem is that the descriptor-ness of a type-level attribute is only checked at opcache-set time, not at opcache-hit time. $ python3.8 test.py 2 $ ./python --version Python 3.10.0a2+ $ git rev-parse --short HEAD 789359f47c $ ./python test.py 1 |
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| msg380374 - (view) | Author: Pablo Galindo Salgado (pablogsal) *  |
Date: 2020-11-04 22:32 | |
Good catch, Kevin! Would you like to submit a PR for fixing this? |
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| msg380375 - (view) | Author: Pablo Galindo Salgado (pablogsal) * |
Date: 2020-11-04 22:37 | |
Given that having attributes that are classes is quite uncommon, I think we can not optimize of the attribute itself is a class instead of checking for descriptors on every hit, hurting the performance gains |
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| msg380376 - (view) | Author: Pablo Galindo Salgado (pablogsal) * |
Date: 2020-11-04 22:49 | |
Yury, any preference here? |
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| msg380378 - (view) | Author: Pablo Galindo Salgado (pablogsal) * |
Date: 2020-11-04 22:53 | |
We could also store the tag of the type object if is a descriptor and compare against that on the cache hit to check that our assumptions are valid. The price here would be an extra pointer on the cache per opcode that may not even be used most of the time. |
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| msg380379 - (view) | Author: Pablo Galindo Salgado (pablogsal) * |
Date: 2020-11-04 23:10 | |
s/the attribute itself is a class/the attribute itself is in the class/ |
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| msg380399 - (view) | Author: Pablo Galindo Salgado (pablogsal) * |
Date: 2020-11-05 09:23 | |
New changeset 80449f243b13311d660eab3a751648029bcdd833 by Pablo Galindo in branch 'master': bpo-42266: Handle monkey-patching descriptors in LOAD_ATTR cache (GH-23157) https://github.com/python/cpython/commit/80449f243b13311d660eab3a751648029bcdd833 |
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