Intermittent test failure on iOS during test_interpreters stress test: RuntimeError: Failed to import encodings module#131485
Description
Bug report
Bug description:
We've seen intermittent failures on the iOS buildbot during the execution of the test_interpreters test:
... test_create_many_sequential (test.test_interpreters.test_stress.StressTests.test_create_many_sequential) ... ok test_create_many_threaded (test.test_interpreters.test_stress.StressTests.test_create_many_threaded) ... ok test_many_threads_running_interp_in_other_interp (test.test_interpreters.test_stress.StressTests.test_many_threads_running_interp_in_other_interp) ... Warning -- Uncaught thread exception: InterpreterError Exception in thread Thread-1571 (run): RuntimeError: Failed to import encodings module During handling of the above exception, another exception occurred: interpreters.InterpreterError: sub-interpreter creation failed During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/Users/buildbot/Library/Developer/XCTestDevices/4F6EA510-4EA0-4706-8B1F-020FE958C08F/data/Containers/Bundle/Application/DBFDCCFF-85B7-4B66-9B7D-D1A7666166D0/iOSTestbed.app/python/lib/python3.14/threading.py", line 1054, in _bootstrap_inner self.run() ~~~~~~~~^^ File "/Users/buildbot/Library/Developer/XCTestDevices/4F6EA510-4EA0-4706-8B1F-020FE958C08F/data/Containers/Bundle/Application/DBFDCCFF-85B7-4B66-9B7D-D1A7666166D0/iOSTestbed.app/python/lib/python3.14/threading.py", line 996, in run self._target(*self._args, **self._kwargs) ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Users/buildbot/Library/Developer/XCTestDevices/4F6EA510-4EA0-4706-8B1F-020FE958C08F/data/Containers/Bundle/Application/DBFDCCFF-85B7-4B66-9B7D-D1A7666166D0/iOSTestbed.app/python/lib/python3.14/test/test_interpreters/test_stress.py", line 47, in run interp = interpreters.create() File "/Users/buildbot/Library/Developer/XCTestDevices/4F6EA510-4EA0-4706-8B1F-020FE958C08F/data/Containers/Bundle/Application/DBFDCCFF-85B7-4B66-9B7D-D1A7666166D0/iOSTestbed.app/python/lib/python3.14/test/support/interpreters/__init__.py", line 76, in create id = _interpreters.create(reqrefs=True) interpreters.InterpreterError: interpreter creation failed ok ---------------------------------------------------------------------- Ran 152 tests in 7.483s OK (skipped=14) 0:05:31 load avg: 4.70 [248/486/1] test_interpreters failed (env changed) The test itself passes seems to pass; the failure that is reported is a change in environment. The test passes on a re-run.
There have been 6 examples of this in the last 2 months:
- https://buildbot.python.org/#/builders/1380/builds/2955
- https://buildbot.python.org/#/builders/1380/builds/2860
- https://buildbot.python.org/#/builders/1380/builds/2813
- https://buildbot.python.org/#/builders/1380/builds/2528
- https://buildbot.python.org/#/builders/1380/builds/2481
- https://buildbot.python.org/#/builders/1380/builds/2425
It has also been observed in 3.13
It's not clear to me if this is an iOS issue (falling apart under the stress), or an issue with the underlying subinterpreter setup that iOS is able to (intermittently) expose. The "Failed to import encodings module" is the bit that gives me pause - There's no diagnostics on why the import failed, but that sort of error would be consistent with a path not being fully configured. It clearly is configured (in the normal case at least), but I'm wondering if having multiple threads start simultaneously could be exposing a leak where one thread thinks something has been configured but another thread is still initialising.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Other