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GeezerVison is showing github.com — fix(tests): explicit yield in test_create_ssl_server_manual_connection_lost by samypr100 · Pull Request #743 · MagicStack/uvloop

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@samypr100

@samypr100 samypr100 commented Apr 4, 2026 •
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This PR fixes test_context.test_create_ssl_server_manual_connection_lost flakiness that became very apparent when using PYTHONASYNCIODEBUG=1 after Python 3.13.12 and 3.14.3. Previous versions are unaffected because they don't contain the patch introduced by python/cpython#141696 although it may still rarely flake on older versions.

After python/cpython#141696 loop.run_in_executor(..., ssl_sock.send) now often resolves without yielding to the event loop when PYTHONASYNCIODEBUG=1 is set. When no yielding happens the SSL incoming buffer never gets the sent data while _app_reading_paused was set to true.

Looking at the test and context when it was introduced in #348, I believe there was an implicit assumption that run_in_executor would yield in this test so that it would go through the expected internal path of epoll_pwait -> buffer_updated_impl before scheduling close flushing process and resume_reading setting _app_reading_paused to false.

Disclosure: This PR is made by human-only contribution without AI generated code.

Note this PR will remain in draft as it relies on #742 to show success of the CI.

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@samypr100 samypr100 mentioned this pull request Apr 4, 2026
fix(build): use packaging instead of relying on pkg_resources from setuptools #742
Merged
This was referenced Apr 25, 2026
feat(loop): support eager_start in loop.create_task #748
Merged
support **kwargs on loop.create_task like in 3.13 and 3.14 #746
Closed
@samypr100
fix: explicit yield after run_in_executor as it was implicitly needed
9d933bb
@samypr100
samypr100 force-pushed the fix-yield branch from de602a5 to 9d933bb Compare April 28, 2026 16:22
@samypr100
samypr100 marked this pull request as ready for review April 28, 2026 16:22
fantix
fantix approved these changes Apr 28, 2026
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@fantix
fantix merged commit 6cd24cb into MagicStack:master Apr 28, 2026
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@samypr100
samypr100 deleted the fix-yield branch April 28, 2026 20:59
@fantix fantix mentioned this pull request Sep 30, 2026
uvloop 0.23.0 #768
Merged
jensbjorgensen pushed a commit to jensbjorgensen/uvloop that referenced this pull request Oct 6, 2026
@fantix
uvloop 0.23.0
c5f7deb 
Changes
=======

* Add Python 3.15 and 3.15t wheel builds and CI coverage (MagicStack#758)
  (by @honglei @fantix in f7c0547)

* Add support for the `eager_start` keyword argument in create_task() (MagicStack#748)
  (by @samypr100 in 3cbb095 for MagicStack#746 MagicStack#718)

* Add thread name prefix to the default thread pool executor (MagicStack#636)
  (by @inikolaev @fantix in 0582f94 for MagicStack#562)

* Add support for special hostname `<broadcast>` (MagicStack#592)
  (by @jpbede in 3060ceb for MagicStack#540)

* Upgrade libuv to v1.52.1 (MagicStack#753)
  (by @fantix in e8efea4 for MagicStack#752)

* Improve performance by using Python C API to enter/exit context (MagicStack#627)
  (by @tarasko in 837ef22)

* Improve performance/latency of Transport.write (MagicStack#619)
  (by @tarasko in 1d9b6e0)

* Replace some SSL vectorcall with direct methods (MagicStack#626)
  (by @tarasko in 6a27cbe)

* Optimize SSL buffered reads using C values (MagicStack#629)
  (by @tarasko in a308f75)

Fixes
=====

* Detach socket on create_connection cancellation to prevent fd double-close (MagicStack#740)
  (by @junjzhang @fantix in dc680eb for MagicStack#645 MagicStack#738)

* Remove `loop._ready_len` in favor of `len(loop._ready)` (MagicStack#721)
  (by @x42005e1f in 5910a18 for MagicStack#720)

* Prefer inspect.iscoroutinefunction (MagicStack#705)
  (by @MatthieuDartiailh in fd65027 for MagicStack#703)

* Fix context tests by explicitly yielding after run_in_executor (MagicStack#743)
  (by @samypr100 in 6cd24cb)

* Fix test_create_connection_open_con_addr with Python 3.13.9+ (MagicStack#713)
  (by @shadchin in b93141a for MagicStack#701)

* Skip flaky test_cancel_post_init on asyncio 3.13+ (MagicStack#714)
  (by @fantix in 3ea5c85 for MagicStack#709)

* Fix flaky test_fs_event (MagicStack#717)
  (by @fantix in 8da4547)

* Use C __atomic builtins for debug counters (MagicStack#719)
  (by @fantix in 836e3b2)

* Update the example to work with Python 3.14 (MagicStack#710)
  (by @Jamie-Chang in b74c2f1)

Build
=====

* Replace pkg_resources with packaging and use Cython 3.1 (MagicStack#742)
  (by @samypr100 in b377b7c for MagicStack#729)

* Remove wheel as a build dependency (MagicStack#696)
  (by @DimitriPapadopoulos in 173e88c)

* Support any number of flags in UVLOOP_OPT_CFLAGS (MagicStack#630)
  (by @mgorny in 963a5f3)
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@fantix fantix fantix approved these changes

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@samypr100 @fantix
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