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Created on 2019-11-22 02:31 by Jake Northey, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| report.py | dirkroorda, 2020-06-30 08:43 | Test of computing max of a shareable list of several sizes, timings for python 3.8.3 and 3.9.0b3 | ||
| Pull Requests | |||
|---|---|---|---|
| URL | Status | Linked | Edit |
| PR 18996 | merged | tkren, 2020-03-14 14:57 | |
| Messages (4) | |||
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| msg357239 - (view) | Author: Jake Northey (Jake Northey) | Date: 2019-11-22 02:31 | |
For an illustration of the performance implications of the __getitem__ and __setitem__ implementation, see the article below. https://medium.com/@rvprasad/performance-of-system-v-style-shared-memory-support-in-python-3-8-d7a7d1b1fb96 The issue appears to be due to the summing of ShareableList item sizes to generate an offset for the requested item. Perhaps an offset-based index could be created in which the allocation sizes could be constructed by comparing two offets. |
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| msg357262 - (view) | Author: Dong-hee Na (corona10) *  |
Date: 2019-11-22 09:45 | |
IMHO, 1. replace self._allocated_bytes to self._sum_allocated_bytes 2. initialize self._sum_allocated_bytes at the __init__ time. 2. if self._allocated_bytes is needed, calculate from _sum_allocated_bytes it will take O(1) If the suggestion is accepted, I'd like to work on this issue. |
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| msg366784 - (view) | Author: Antoine Pitrou (pitrou) * |
Date: 2020-04-19 15:19 | |
New changeset c8f1715283ec51822fb37a702bf253cbac1af276 by Thomas Krennwallner in branch 'master': bpo-38891: avoid quadratic item access performance of ShareableList (GH-18996) https://github.com/python/cpython/commit/c8f1715283ec51822fb37a702bf253cbac1af276 |
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| msg372665 - (view) | Author: Dirk Roorda (dirkroorda) * | Date: 2020-06-30 08:43 | |
I can see that the performance of ShareableList is much better now. Still the performance of list operations on a ShareableList may be degraded by a factor 200-300 with respect to a normal list. If this is unavoidable then the docs should clearly mention this degradation, because this will, in many use cases, cancel the performance gain that shared memory offers! |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:23 | admin | set | github: 83072 |
| 2020-06-30 08:43:24 | dirkroorda | set | files:
+ report.py nosy: + dirkroorda messages: + msg372665 |
| 2020-04-19 15:19:42 | pitrou | set | status: open -> closed resolution: fixed stage: patch review -> resolved |
| 2020-04-19 15:19:28 | pitrou | set | nosy:
+ pitrou messages: + msg366784 |
| 2020-04-18 18:39:27 | pitrou | set | versions: + Python 3.9, - Python 3.8 |
| 2020-03-14 14:57:40 | tkren | set | keywords:
+ patch nosy: + tkren pull_requests: + pull_request18343 stage: patch review |
| 2019-11-22 09:45:31 | corona10 | set | nosy:
+ corona10 messages: + msg357262 |
| 2019-11-22 02:31:14 | Jake Northey | create | |