Improve performance of starting request handlers with Python 3.12+

[bdraco]

What do these changes do?

#3406 wrapped _handle_request in a task to copy the contextvars which delays the start of the request by one iteration of the event loop and increases event loop overhead by forcing it to be scheduled which many of the handlers can finish synchronously.

In #8170 (reply in thread) we did not have a way to improve with without removing the task, however since Python 3.12+ has eager start for tasks, we can now avoid the delay and scheduling overhead.

Are there changes in behavior for the user?

Performance improvement

Is it a substantial burden for the maintainers to support this?

no

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.97%. Comparing base (6c6ecfa) to head (a4a0dd3).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8661   +/-   ##
=======================================
  Coverage   97.97%   97.97%           
=======================================
  Files         107      107           
  Lines       33780    33784    +4     
  Branches     3966     3967    +1     
=======================================
+ Hits        33096    33100    +4     
  Misses        507      507           
  Partials      177      177           

Flag	Coverage Δ
CI-GHA	97.88% <80.00%> (-0.01%)	⬇️
OS-Linux	97.54% <80.00%> (-0.01%)	⬇️
OS-Windows	95.91% <80.00%> (-0.01%)	⬇️
OS-macOS	97.20% <80.00%> (-0.01%)	⬇️
Py-3.10.11	97.34% <60.00%> (-0.01%)	⬇️
Py-3.10.14	97.28% <60.00%> (-0.01%)	⬇️
Py-3.11.9	97.51% <60.00%> (-0.01%)	⬇️
Py-3.12.4	97.62% <60.00%> (-0.01%)	⬇️
Py-3.8.10	95.55% <60.00%> (-0.01%)	⬇️
Py-3.8.18	97.06% <60.00%> (-0.01%)	⬇️
Py-3.9.13	97.21% <60.00%> (-0.01%)	⬇️
Py-3.9.19	97.15% <60.00%> (-0.01%)	⬇️
Py-pypy7.3.16	96.74% <60.00%> (-0.01%)	⬇️
VM-macos	97.20% <80.00%> (-0.01%)	⬇️
VM-ubuntu	97.54% <80.00%> (-0.01%)	⬇️
VM-windows	95.91% <80.00%> (-0.01%)	⬇️

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[bdraco]

Thanks

[patchback]

Backport to 3.10: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 4d604ea on top of patchback/backports/3.10/4d604eafefbee22ad35886c3bd12e4c3048cc45b/pr-8661

Backporting merged PR #8661 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.10/4d604eafefbee22ad35886c3bd12e4c3048cc45b/pr-8661 upstream/3.10

4. Now, cherry-pick PR Improve performance of starting request handlers with Python 3.12+ #8661 contents into that branch:

   $ git cherry-pick -x 4d604eafefbee22ad35886c3bd12e4c3048cc45b

   If it'll yell at you with something like fatal: Commit 4d604eafefbee22ad35886c3bd12e4c3048cc45b is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 4d604eafefbee22ad35886c3bd12e4c3048cc45b

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Improve performance of starting request handlers with Python 3.12+ #8661 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.10/4d604eafefbee22ad35886c3bd12e4c3048cc45b/pr-8661

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 4d604ea on top of patchback/backports/3.11/4d604eafefbee22ad35886c3bd12e4c3048cc45b/pr-8661

Backporting merged PR #8661 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.11/4d604eafefbee22ad35886c3bd12e4c3048cc45b/pr-8661 upstream/3.11

4. Now, cherry-pick PR Improve performance of starting request handlers with Python 3.12+ #8661 contents into that branch:

   $ git cherry-pick -x 4d604eafefbee22ad35886c3bd12e4c3048cc45b

   If it'll yell at you with something like fatal: Commit 4d604eafefbee22ad35886c3bd12e4c3048cc45b is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 4d604eafefbee22ad35886c3bd12e4c3048cc45b

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Improve performance of starting request handlers with Python 3.12+ #8661 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/4d604eafefbee22ad35886c3bd12e4c3048cc45b/pr-8661

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.