`test.test_ssl.ThreadedTests.test_sendfile` times out on i686 build of 3.15.0a1 in Fedora

[befeleme]

Bug report

Bug description:

On Fedora Linux 44, the built i686 debug Python 3.15.0a1 fails the test.regrtest, as test_sendfile times out:

test_sendfile (test.test_ssl.ThreadedTests.test_sendfile)
Try to send a file using kTLS if possible. ... kTLS is available
Timeout (0:45:00)!
Thread 0xf1effb40 [Thread-221] (most recent call first):
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/ssl.py", line 1155 in read
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/test_ssl.py", line 2484 in read
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/test_ssl.py", line 2507 in run
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/threading.py", line 1075 in _bootstrap_inner
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/threading.py", line 1037 in _bootstrap
Thread 0xf16feb40 [Thread-220] (most recent call first):
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/threading.py", line 1126 in join
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/test_ssl.py", line 2673 in run
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/threading.py", line 1075 in _bootstrap_inner
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/threading.py", line 1037 in _bootstrap
Thread 0xf7585700 [python] (most recent call first):
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/ssl.py", line 1155 in read
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/ssl.py", line 1335 in recv
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/test_ssl.py", line 4603 in test_sendfile
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/case.py", line 613 in _callTestMethod
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/case.py", line 667 in run
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/case.py", line 723 in __call__
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/suite.py", line 122 in run
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/suite.py", line 84 in __call__
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/suite.py", line 122 in run
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/suite.py", line 84 in __call__
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/unittest/runner.py", line 257 in run
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 84 in _run_suite
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 42 in run_unittest
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 162 in test_func
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 118 in regrtest_runner
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 165 in _load_run_test
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 210 in _runtest_env_changed_exc
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 319 in _runtest
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/single.py", line 348 in run_single_test
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/worker.py", line 92 in worker_process
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/worker.py", line 127 in main
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/test/libregrtest/worker.py", line 131 in <module>
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/runpy.py", line 88 in _run_code
  File "/builddir/build/BUILD/python3.15-3.15.0_a1-build/Python-3.15.0a1/Lib/runpy.py", line 198 in _run_module_as_main
1 test failed again:
    test_ssl

CPython versions tested on:

3.15

Operating systems tested on:

Linux

[hroncok]

Full build.log.

This also seem to happen on all Fedora versions (41 to 44).

[picnixz]

I guess it's a regression in 5a20e79? cc @illia-v

[illia-v]

Reaching "line 4603 in test_sendfile" suggests that the SSL_sendfile call had to succeed, but it was not possible to get a further response from the server.

cpython/Lib/test/test_ssl.py

Lines 4601 to 4603 in 38d4b43

	with open(os_helper.TESTFN, 'rb') as file:
	ssock.sendfile(file)
	self.assertEqual(ssock.recv(1024), TEST_DATA)

It's possible that the issue is not related to the sendfile change, but to any reads/writes which use kTLS. CPython has been supporting ssl.OP_ENABLE_KTLS since 3.12, but the flag was not set in any tests.
It may be worth checking if other test_ssl tests succeeed when ssl.OP_ENABLE_KTLS is set in CPython 3.12+ on i686. I don't have access to any i686 machine, unfortunatelly.

[hroncok]

I don't have access to any i686 machine, unfortunately.

I'd say (almost) nobody does nowadays. Anyway, I am trying to crosscompile ix86 Python on x86_64 Fedora, but I keep getting no _ssl module.