Crash During Subinterpreter Finalization

[ericsnowcurrently]

There's an isolation leak somewhere. It may be just in the _xxsubinterpreters module, but I suspect it's not.

See #99114 (comment).

Reproducers:

• https://gist.github.com/tonybaloney/262986212e1061b97908657a53a605d6
• https://gist.github.com/tonybaloney/504be6d1541610f50963c32a3f1c379d

FYI, I see crashes on this fairly infrequently.

Linked PRs

• gh-105699: Use a Thread-Local Variable for PKGCONTEXT #105740
• [3.12] gh-105699: Use a Thread-Local Variable for PKGCONTEXT (gh-105740) #105765
• gh-105699: Use a Linked List for the PyModuleDef Cache #106899
• gh-105699: Fix a Crasher Related to a Deprecated Global Variable #106923
• gh-105699: Fix an Interned Strings Crasher #106930
• [3.12] gh-105699: Fix an Interned Strings Crasher (gh-106930) #106963
• [3.12] gh-105699: Fix a Crasher Related to a Deprecated Global Variable (gh-106923) #106964
• gh-105699: Add Some Stress Tests for Subinterpreter Creation #106966
• gh-105699: Use a _Py_hashtable_t for the PyModuleDef Cache #106974
• [3.12] gh-105699: Add some stress tests for subinterpreter creation (GH-106966) #107012
• gh-105699: Disable the Interpreters Stress Tests #107354
• [3.12] gh-105699: Disable the Interpreters Stress Tests (gh-107354) #107357
• [3.12] gh-105699: Use a _Py_hashtable_t for the PyModuleDef Cache (gh-106974) #107412
• gh-105699: Re-enable the Multiple-Interpreters Stress Tests #107572
• [3.12] gh-105699: Re-enable the Multiple-Interpreters Stress Tests (gh-107572) #107783
• [3.12] gh-105699: Re-enable the Multiple-Interpreters Stress Tests (gh-107572) #112483

[ericsnowcurrently]

Probably the same thing:

(AMD64 Arch Linux TraceRefs 3.12)

test_one (test.test__xxsubinterpreters.DestroyTests.test_one) ... ok
Objects/object.c:2211: _Py_ForgetReference: Assertion failed: invalid object chain
Enable tracemalloc to get the memory block allocation traceback
object address  : 0x7f6bf962d300
object refcount : 0
object type     : 0x55a320cd18c0
object type name: bytes
object repr     : <refcnt 0 at 0x7f6bf962d300>
Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: initialized
Current thread 0x00007f6c09e2e740 (most recent call first):
  <no Python frame>
Debug memory block at address p=0x7f6c09d55e90: API '�'
    18302063728033398269 bytes originally requested
    The 7 pad bytes at p-7 are not all FORBIDDENBYTE (0xfd):
        at p-7: 0xdd *** OUCH
        at p-6: 0xdd *** OUCH
        at p-5: 0xdd *** OUCH
        at p-4: 0xdd *** OUCH
        at p-3: 0xdd *** OUCH
        at p-2: 0xdd *** OUCH
        at p-1: 0xdd *** OUCH
    Because memory is corrupted at the start, the count of bytes requested
       may be bogus, and checking the trailing pad bytes may segfault.
    The 8 pad bytes at tail=0xfdfe7d6a07d35c8d are Fatal Python error: Segmentation fault
Current thread 0x00007f6c09e2e740 (most recent call first):
  <no Python frame>
Extension modules: _testcapi, _xxsubinterpreters, _xxinterpchannels (total: 3)
make: *** [Makefile:2015: buildbottest] Segmentation fault (core dumped)

[ericsnowcurrently]

maybe related: #105690