[Django] #35229: Prevent repeated checks of custom error handler URLs

[Django]

#35229: Prevent repeated checks of custom error handler URLs
------------------------------------------------+--------------------------
Reporter: Adam Johnson | Owner: nobody
Type: Cleanup/optimization | Status: assigned
Component: Core (System checks) | Version: dev
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 1
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
------------------------------------------------+--------------------------
In #29642 I added a system check for custom error handler URLs.

I looked at a profile for running the system checks on a project and found
this check function ran hundreds of times rather than once, totalling 1/4
of the time to run checks. The multiple runs occur because the check is
defined on `URLResolver`, of which exist in a tree structure. Moving the
check from `URLResolver` to a function in `django.core.checks.urls`
ensures it runs only once.

In the profiled project with 279 URLs, this takes the checks from ~24ms to
~21ms, a ~13% saving.
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Ticket URL: <https://code.djangoproject.com/ticket/35229>
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[Django]

#35229: Prevent repeated checks of custom error handler URLs

--------------------------------------+------------------------------------

Reporter: Adam Johnson | Owner: nobody
Type: Cleanup/optimization | Status: assigned
Component: Core (System checks) | Version: dev

Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

--------------------------------------+------------------------------------
Changes (by Simon Charette):

* stage: Unreviewed => Accepted

Comment:

Do you think it might be worth adding
[https://github.com/django/djangobench/tree/master/djangobench/benchmarks
a check running benchmark] as well?
--
Ticket URL: <https://code.djangoproject.com/ticket/35229#comment:1>

[Django]

#35229: Prevent repeated checks of custom error handler URLs
--------------------------------------+------------------------------------
Reporter: Adam Johnson | Owner: nobody
Type: Cleanup/optimization | Status: assigned
Component: Core (System checks) | Version: dev
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------------+------------------------------------

Comment (by Adam Johnson):

It would be nice, but it’s very hard. Many of the performance problems
will only appear with scale, with many related models, URLs, etc. I think,
for now, it’s more fruitful to profile running checks on real projects.

By the way, this burst of optimization tickets is inspired by a Mastodon
discussion about disabling checks because of their slowness:
https://mastodon.social/@webology/111715052165307624 . I decided to
profile a client project yesterday and work on the clear hot spots.
--
Ticket URL: <https://code.djangoproject.com/ticket/35229#comment:2>

[Django]

#35229: Prevent repeated checks of custom error handler URLs

-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
Type: | Johnson
Cleanup/optimization | Status: assigned
Component: Core (System | Version: dev
checks) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Ready for
| checkin

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

-------------------------------------+-------------------------------------
Changes (by Mariusz Felisiak):

* owner: nobody => Adam Johnson
* stage: Accepted => Ready for checkin

--
Ticket URL: <https://code.djangoproject.com/ticket/35229#comment:3>

[Django]

#35229: Prevent repeated checks of custom error handler URLs
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
Type: | Johnson

Cleanup/optimization | Status: closed

Component: Core (System | Version: dev
checks) |

Severity: Normal | Resolution: fixed

Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by GitHub <noreply@…>):

* resolution: => fixed
* status: assigned => closed

Comment:

In [changeset:"28a3fbe0048883fdd5cefd6ffecb88e351121891" 28a3fbe]:
{{{#!CommitTicketReference repository=""
revision="28a3fbe0048883fdd5cefd6ffecb88e351121891"
Fixed #35229 -- Made URL custom error handler check run once.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35229#comment:4>