gh-74112: Fix race in test_interrupt_blocking_call by christianaurichzm · Pull Request #158914 · python/cpython · GitHub

InterruptTest.test_interrupt_blocking_call (added in gh-157662) started the timer that sends SIGINT before entering the assertRaises() block:

timer.start()
start = time.monotonic()
with self.assertRaises(KeyboardInterrupt):
    time.sleep(support.SHORT_TIMEOUT)

If the main thread takes more than 0.1 seconds to get from timer.start() to time.sleep(), the KeyboardInterrupt is raised outside the block. It escapes the test, and regrtest stops the whole run ("Test suite interrupted by signal SIGINT"). This happened on the AMD64 Windows Server 2022 NoGIL buildbot, as reported in gh-74112, and in the "macOS (free-threading)" job on #158910 and #158828. In all three cases the build was free-threaded and the machine was loaded.

This change starts the timer inside the block, so the interrupt is caught wherever it arrives.

Verification

I ran the real test 300 times in a loop on a free-threaded debug build, with 48 busy processes on 16 cores:

before: the KeyboardInterrupt escaped the test in 46 out of 300 runs
after: 0 out of 300

On the default build it did not reproduce under the same load (0 out of 500 before and after). There the timer thread needs the GIL to send the signal, which in practice hides the window. test_idle passes on both builds.

Issue: IDLE: in shell, time.sleep ignores _thread.interrupt_main() #74112

The timer that sends SIGINT was started before entering the assertRaises() block. On a loaded machine the KeyboardInterrupt could be raised before the main thread reached time.sleep(), escape the test and stop the whole regrtest run. Start the timer inside the block.

LGTM. 👍 Thank you for the analysis and the fix.

Thanks @christianaurichzm for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15.
🐍🍒⛏🤖

Sorry, @christianaurichzm and @serhiy-storchaka, I could not cleanly backport this to 3.15 due to a conflict.

Please backport manually with cherry_picker, see the devguide for more information.

cherry_picker ea0ee925ad755999d6095ba61de2652ec9275f04 3.15

GH-158920 is a backport of this pull request to the 3.14 branch.

…8914) On a loaded machine the KeyboardInterrupt could be raised before the main thread reached time.sleep(), escape the test and stop the whole regrtest run. (cherry picked from commit ea0ee92)

I cherry-picked this change in #158917, so no separate backport to 3.15 is needed.

…GH-158920) On a loaded machine the KeyboardInterrupt could be raised before the main thread reached time.sleep(), escape the test and stop the whole regrtest run. (cherry picked from commit ea0ee92) Co-authored-by: Christian Aurich Zanettini Martins <christian.aurichzm@gmail.com>

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 Fedora Stable Refleaks 3.x (tier-2) has failed when building commit ea0ee92.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/123/builds/2520) and take a look at the build logs.
Check if the failure is related to this commit (ea0ee92) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/123/builds/2520

Failed tests:

test_profiling
test.test_asyncio.test_events

Failed subtests:

test_cprofile - test.test_profile.ProfileTest.test_cprofile
test_create_connection_local_addr_skip_different_family - test.test_asyncio.test_events.SelectEventLoopTests.test_create_connection_local_addr_skip_different_family

Test leaking resources:

test_manager: references
test_manager: memory blocks

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64.refleak/build/Lib/test/test_asyncio/test_events.py", line 825, in test_create_connection_local_addr_skip_different_family
    with self.assertRaises(OSError):
         ~~~~~~~~~~~~~~~~~^^^^^^^^^
AssertionError: OSError not raised


Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64.refleak/build/Lib/test/test_profile.py", line 70, in test_cprofile
    self.fail("\n".join(fail))
    ~~~~~~~~~^^^^^^^^^^^^^^^^^
AssertionError: 
Stats.print_stats output for Profile does not fit expectation:
--- 
+++ 
@@ -1,7 +1,7 @@
        28   27.972    0.999   27.972    0.999 profilee.py:110(__getattr__)
-        1  269.996  269.996  999.769  999.769 profilee.py:25(testfunc)
-     23/3  149.937    6.519  169.917   56.639 profilee.py:35(factorial)
-       20   19.980    0.999   19.980    0.999 profilee.py:48(mul)
+        1  269.997  269.997  999.816  999.816 profilee.py:25(testfunc)
+     20/3  163.969    8.198  169.963   56.654 profilee.py:35(factorial)
+        6    5.994    0.999    5.994    0.999 profilee.py:48(mul)
         2   39.986   19.993  599.830  299.915 profilee.py:55(helper)
         4  115.984   28.996  119.964   29.991 profilee.py:73(helper1)
         2   -0.006   -0.003  139.946   69.973 profilee.py:84(helper2_indirect)


Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64.refleak/build/Lib/test/support/__init__.py", line 970, in gc_collect
    gc.collect()
    ~~~~~~~~~~^^
ResourceWarning: unclosed <socket.socket fd=5, family=2, type=1, proto=6, laddr=('127.0.0.1', 57745), raddr=('127.0.0.1', 57745)>
Warning -- Unraisable exception
Exception ignored while calling deallocator <function _SelectorTransport.__del__ at 0xffff8e8abad0>:
Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64.refleak/build/Lib/asyncio/selector_events.py", line 882, in __del__
    _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
    ~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ResourceWarning: unclosed transport <_SelectorSocketTransport fd=5>

christianaurichzm requested a review from terryjreedy as a code owner October 6, 2026 14:40

bedevere-app Bot mentioned this pull request Oct 6, 2026

IDLE: in shell, time.sleep ignores _thread.interrupt_main() #74112

Closed

bedevere-app Bot added awaiting review tests Tests in the Lib/test dir labels Oct 6, 2026

christianaurichzm mentioned this pull request Oct 6, 2026

gh-158803: Fix crash in bytes.join() on a concurrently mutated list #158910

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serhiy-storchaka approved these changes Oct 6, 2026

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bedevere-app Bot added awaiting merge and removed awaiting review labels Oct 6, 2026

serhiy-storchaka added needs backport to 3.13 only security fixes needs backport to 3.14 bugs and security fixes skip news needs backport to 3.15 pre-release feature fixes, bugs and security fixes and removed needs backport to 3.13 only security fixes labels Oct 6, 2026

serhiy-storchaka enabled auto-merge (squash) October 6, 2026 15:03

serhiy-storchaka merged commit ea0ee92 into python:main Oct 6, 2026
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bedevere-app Bot removed the awaiting merge label Oct 6, 2026

miss-islington-app Bot assigned serhiy-storchaka Oct 6, 2026

bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Oct 6, 2026

serhiy-storchaka removed the needs backport to 3.15 pre-release feature fixes, bugs and security fixes label Oct 6, 2026

gh-74112: Fix race in test_interrupt_blocking_call by christianaurichzm · Pull Request #158914 · python/cpython · GitHub

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gh-74112: Fix race in test_interrupt_blocking_call - #158914

gh-74112: Fix race in test_interrupt_blocking_call#158914
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gh-74112: Fix race in test_interrupt_blocking_call by christianaurichzm · Pull Request #158914 · python/cpython · GitHub

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gh-74112: Fix race in test_interrupt_blocking_call#158914
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