test_concurrent_futures.test_interpreter_pool failing

[ericsnowcurrently]

Bug report

Bug description:

I've seen 4 kinds of failure which I'm failure sure have the same cause:

• segfault during WorkerContext.initialize() (line 137)
• hanging
• weird test failure
• undefined behavior on USAN buildbot

The failures have happened in different test methods. Different failures have happened during the retry. Sometimes the retry passes. In all cases the architecture is AMD64, but across a variety of builders and non-Windows operating systems. The failures have all been on either refleaks buildbots or the USAN buildbot.

FWIW, it looks like InterpreterPoolExecutor has only exposed an underlying problem in the _interpqueues module, which means any fix would need to target 3.13 also (and maybe 3.12).

---

Here are the buildbots where I've seen failures:

• AMD64 RHEL8 Refleaks 3.x
• AMD64 FreeBSD Refleaks 3.x
• AMD64 CentOS9 NoGIL Refleaks 3.x
• AMD64 Arch Linux Usan Function 3.x

Here's the failure text:

segfault

test_submit (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_submit) ... Fatal Python error:

Segmentation fault
Current thread 0x00007fb4fbfff700 (most recent call first):
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/concurrent/futures/interpreter.py", line 137 in initialize
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/concurrent/futures/thread.py", line 98 in _worker
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/threading.py", line 992 in run
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007fb521d71240 (most recent call first):
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/threading.py", line 359 in wait
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/concurrent/futures/_base.py", line 443 in result
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/test_concurrent_futures/executor.py", line 31 in test_submit
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/case.py", line 606 in _callTestMethod
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/case.py", line 660 in run
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/case.py", line 716 in __call__
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/suite.py", line 122 in run
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/suite.py", line 84 in __call__
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/suite.py", line 122 in run File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/suite.py", line 84 in __call__
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/unittest/runner.py", line 240 in run
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 57 in _run_suite
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 37 in run_unittest
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 135 in test_func
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/refleak.py", line 132 in runtest_refleak
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 87 in regrtest_runner
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 138 in _load_run_test
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 181 in _runtest_env_changed_exc
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 281 in _runtest
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/single.py", line 310 in run_single_test
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/worker.py", line 83 in worker_process
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/worker.py", line 118 in main
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/test/libregrtest/worker.py", line 122 in <module>
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/runpy.py", line 88 in _run_code
 File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.refleak/build/Lib/runpy.py", line 198 in _run_module_as_main

hang 1

test_submit_exception_in_func (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_submit_exception_in_func) ... Timeout (3:20:00)!

Thread 0x000000082e546e00 (most recent call first): File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/concurrent/futures/interpreter.py", line 190 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/concurrent/futures/thread.py", line 85 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/concurrent/futures/thread.py", line 118 in _worker
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/threading.py", line 992 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x0000000825a7c000 (most recent call first):
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/threading.py", line 359 in wait
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/concurrent/futures/_base.py", line 443 in result
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/test_concurrent_futures/test_interpreter_pool.py", line 251 in test_submit_exception_in_func
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/case.py", line 606 in _callTestMethod
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/case.py", line 660 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/case.py", line 716 in __call__
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/suite.py", line 122 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/suite.py", line 84 in __call__
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/suite.py", line 122 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/suite.py", line 84 in __call__
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/unittest/runner.py", line 240 in run
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 57 in _run_suite
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 37 in run_unittest
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 135 in test_func
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/refleak.py", line 132 in runtest_refleak
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 87 in regrtest_runner
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 138 in _load_run_test
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 181 in _runtest_env_changed_exc
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 281 in _runtest
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/single.py", line 310 in run_single_test
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/worker.py", line 83 in worker_process
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/worker.py", line 118 in main
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/libregrtest/worker.py", line 122 in <module>
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/runpy.py", line 88 in _run_code
 File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/runpy.py", line 198 in _run_module_as_main

hang 2

test_shutdown_race_issue12456 (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_shutdown_race_issue12456) ... Exception in initializer:
RuntimeError: Failed to import encodings module

During handling of the above exception, another exception occurred:

interpreters.Interpreter Error: sub-interpreter creation failed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/thread.py", line 98, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/interpreter.py", line 131, in initialize
 self.interpid = _interpreters.create(reqrefs=True)
 ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
interpreters.InterpreterError: interpreter creation failed
Timeout (0:45:00)!

Thread 0x00007fe3febe2640 (most recent call first):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/thread.py", line 115 in _worker
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 992 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007fe3fcbda640 (most recent call first):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/thread.py", line 115 in _worker
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 992 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007fe3e77fe640 (most recent call first):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/thread.py", line 115 in _worker
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 992 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007fe3e7fff640 (most recent call first):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/thread.py", line 115 in _worker
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 992 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007fe3ffe6f740 (most recent call first):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/threading.py", line 1092 in join
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/concurrent/futures/thread.py", line 272 in shutdown
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/test_concurrent_futures/executor.py", line 79 in test_shutdown_race_issue12456
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/case.py", line 606 in _callTestMethod
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/case.py", line 660 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/case.py", line 716 in __call__
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/suite.py", line 122 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/suite.py", line 84 in __call__
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/suite.py", line 122 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/suite.py", line 84 in __call__
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/unittest/runner.py", line 240 in run
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 57 in _run_suite
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 37 in run_unittest
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 135 in test_func
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/refleak.py", line 132 in runtest_refleak
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 87 in regrtest_runner
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 138 in _load_run_test
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 181 in _runtest_env_changed_exc
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 281 in _runtest
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/single.py", line 310 in run_single_test
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/worker.py", line 83 in worker_process
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/worker.py", line 118 in main
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/libregrtest/worker.py", line 122 in <module>
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/runpy.py", line 88 in _run_code
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/runpy.py", line 198 in _run_module_as_main

test failed

======================================================================
FAIL: test_free_reference (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_free_reference)
----------------------------------------------------------------------
Traceback (most recent call last):
 File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.refleak.nogil/build/Lib/test/test_concurrent_futures/executor.py", line 132, in test_free_reference
 self.assertIsNone(wr())
 ~~~~~~~~~~~~~~~~~^^^^^^
AssertionError: <test.test_concurrent_futures.executor.MyObject object at 0x200121a00a0> is not None

USAN

test_map_exception (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_map_exception) ... Python/thread_pthread.h:555:42: runtime error: null pointer passed as argument 1, which is declared to never be null
/usr/include/semaphore.h:55:36: note: nonnull attribute specified here
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior Python/thread_pthread.h:555:42 in 
Fatal Python error: Segmentation fault

Thread 0x00007f89aedfd6c0 (most recent call first): File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/interpreter.py", line 131 in initialize
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/thread.py", line 98 in _worker
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 992 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007f89adcfb6c0 (most recent call first): File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/interpreter.py", line 131 in initialize
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/thread.py", line 98 in _worker
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 992 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1012 in _bootstrap

Current thread 0x00007f89af7fe6c0 (most recent call first): File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/interpreter.py", line 137 in initialize
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/thread.py", line 98 in _worker
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 992 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007f89ad4fa6c0 (most recent call first): File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/interpreter.py", line 131 in initialize
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/thread.py", line 98 in _worker
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 992 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1041 in _bootstrap_inner
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 1012 in _bootstrap

Thread 0x00007f89b64500c0 (most recent call first):
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/threading.py", line 359 in wait
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/_base.py", line 443 in result
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/_base.py", line 309 in _result_or_cancel
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/concurrent/futures/_base.py", line 611 in result_iterator
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/test_concurrent_futures/executor.py", line 54 in test_map_exception
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/case.py", line 606 in _callTestMethod
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/case.py", line 660 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/case.py", line 716 in __call__
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/suite.py", line 122 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/suite.py", line 84 in __call__
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/suite.py", line 122 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/suite.py", line 84 in __call__
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/unittest/runner.py", line 240 in run
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 57 in _run_suite
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 37 in run_unittest
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 135 in test_func
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 91 in regrtest_runner
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 138 in _load_run_test
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 181 in _runtest_env_changed_exc
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 281 in _runtest
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/single.py", line 310 in run_single_test
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/worker.py", line 83 in worker_process
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/worker.py", line 118 in main
 File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Lib/test/libregrtest/worker.py", line 122 in <module>
 File "<frozen runpy>", line 88 in _run_code
 File "<frozen runpy>", line 198 in _run_module_as_main

Extension modules: _testinternalcapi (total: 1)
UndefinedBehaviorSanitizer:DEADLYSIGNAL
==2260212==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x03e800227cf4 (pc 0x7f89b64e1194 bp 0x7f89af7fd370 sp 0x7f89af7fd330 T2260241)
==2260212==The signal is caused by a READ memory access.
 #0 0x7f89b64e1194 (/usr/lib/libc.so.6+0x90194) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
 #1 0x7f89b648dd6f in raise (/usr/lib/libc.so.6+0x3cd6f) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
 #2 0x555a15c75b3d in faulthandler_fatal_error /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/./Modules/faulthandler.c:338:5
 #3 0x7f89b648de1f (/usr/lib/libc.so.6+0x3ce1f) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
 #4 0x7f89b64e7504 in sem_wait (/usr/lib/libc.so.6+0x96504) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
 #5 0x555a15c3e86b in PyThread_acquire_lock_timed /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Python/thread_pthread.h:555:33
 #6 0x7f89b47308c6 in _queues_add /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/./Modules/_interpqueuesmodule.c:909:5
 #7 0x7f89b47308c6 in queue_create /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/./Modules/_interpqueuesmodule.c:1103:19
 #8 0x7f89b47308c6 in queuesmod_create /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/./Modules/_interpqueuesmodule.c:1487:19
 #9 0x555a157a3caa in cfunction_call /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Objects/methodobject.c:551:18
 #10 0x555a15677105 in _PyObject_MakeTpCall /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Objects/call.c:242:18
 #11 0x555a15a556ef in _PyEval_EvalFrameDefault /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Python/generated_cases.c.h:2759:35
 #12 0x555a15680c7c in _PyObject_VectorcallTstate /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/./Include/internal/pycore_call.h:167:11
 #13 0x555a1567e32f in method_vectorcall /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Objects/classobject.c:71:20
 #14 0x555a15da9af5 in thread_run /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/./Modules/_threadmodule.c:337:21
 #15 0x555a15c3f5f3 in pythread_wrapper /buildbot/buildarea/3.x.pablogsal-arch-x86_64.clang-ubsan-function/build/Python/thread_pthread.h:242:5
 #16 0x7f89b64df1ce (/usr/lib/libc.so.6+0x8e1ce) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
 #17 0x7f89b65606eb (/usr/lib/libc.so.6+0x10f6eb) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)

UndefinedBehaviorSanitizer can not provide additional info.
SUMMARY: UndefinedBehaviorSanitizer: SEGV (/usr/lib/libc.so.6+0x90194) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
==2260212==ABORTING

CC @encukou

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-125716: Raise an Exception If _globals_init() Fails In the _interpqueues Module #125802
• gh-125716: Use A Global Mutex When Initializing Global State For The _interpqueues Module #125803
• [3.13] gh-125716: Raise an Exception If _globals_init() Fails In the _interpqueues Module (gh-125802) #125808
• [3.13] gh-125716: Use a Global Mutex When Initializing Global State For the _interpqueues Module #125817

[ZeroIntensity]

I've been looking into this for the past hour or so, and I wasn't able to reproduce a segfault, nor do any debuggers detect any foul play.

However, I was able to get this assertion to fail after sending a CTRL+C to unittest. That, and running test_interpreter_pool with a TSan build causes it to absolutely explode with errors, but I wouldn't be surprised if they were all false positives--TSan is far from perfect (do we even support it on GIL-ful builds?)

[rruuaanng]

Oh, it turns out this is a BUG. I triggered this while implementing the PR.

[ericsnowcurrently]

The biggest clue is what the USAN buildbot tells us:

• a NULL pointer is being passed to sem_wait()
• the pointer points to uninitialized/deallocated memory
• the failure happens when the executor's worker context is initialized and calls _interpqueues.create()

Python/thread_pthread.h:555:42: runtime error: null pointer passed as argument 1, which is declared to never be null
/usr/include/semaphore.h:55:36: note: nonnull attribute specified here
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior Python/thread_pthread.h:555:42 in 

Current thread 0x00007f89af7fe6c0 (most recent call first):
 File "Lib/concurrent/futures/interpreter.py", line 137 in initialize

==2260212==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x03e800227cf4
==2260212==The signal is caused by a READ memory access.
 #4 0x7f89b64e7504 in sem_wait (/usr/lib/libc.so.6+0x96504) (BuildId: 915eeec6439cfded1125deefc44a8d73e57873d9)
 #5 0x555a15c3e86b in PyThread_acquire_lock_timed Python/thread_pthread.h:555:33
 #6 0x7f89b47308c6 in _queues_add Modules/_interpqueuesmodule.c:909:5
 #7 0x7f89b47308c6 in queue_create Modules/_interpqueuesmodule.c:1103:19
 #8 0x7f89b47308c6 in queuesmod_create Modules/_interpqueuesmodule.c:1487:19

The pointer in question is the mutex created in _globals_init(), which is called by the module exec function the first time the module is loaded. The mutex is cleared (in _globals_fini()) when the last copy of the module is cleared.

There is a unlikely-but-possible race there in _globals_init() with the module count, which may play a part here. It would make sense to do the following:

• make the lock a PyMutex
• use atomic operations for the module count

That may improve the situation. However, it would be best if we could definitively determine why the mutex is NULL when it shouldn't be.

[ZeroIntensity]

Something that could possibly be related: I've noticed an issue with exceptions inside subinterpreters created by _interpreters that causes them to finalize earlier than they should--depending on what's going on, that could explain the NULL mutex. I'm investigating to see if that's an issue on my end, or something deeper.