Currently, during runtime destruction, `_PyImport_Cleanup` is clearing the interpreter state before clearing out the modules themselves. This leads to a segfault on modules that rely on the module state to clear themselves up.
For example, let's take the small snippet added in the issue by @DinoV :
```
import _struct
class C:
def __init__(self):
self.pack = _struct.pack
def __del__(self):
self.pack('I', -42)
_struct.x = C()
```
The module `_struct` uses the module state to run `pack`. Therefore, the module state has to be alive until after the module has been cleared out to successfully run `C.__del__`. This happens at line 606, when `_PyImport_Cleanup` calls `_PyModule_Clear`. In fact, the loop that calls `_PyModule_Clear` has in its comments:
> Now, if there are any modules left alive, clear their globals to minimize potential leaks. All C extension modules actually end up here, since they are kept alive in the interpreter state.
That means that we can't clear the module state (which is used by C Extensions) before we run that loop.
Moving `_PyInterpreterState_ClearModules` until after it, fixes the segfault in the code snippet.
Finally, this updates a test in `io` to correctly assert the error that it now throws (since it now finds the io module state). The test that uses this is: `test_create_at_shutdown_without_encoding`. Given this test is now working is a proof that the module state now stays alive even when `__del__` is called at module destruction time. Thus, I didn't add a new tests for this.
https://bugs.python.org/issue38076
Move the following functions from the public C API to the internal C
API:
* _PyDebug_PrintTotalRefs(),
* _Py_PrintReferenceAddresses()
* _Py_PrintReferences()
PyThreadState.on_delete is a callback used to notify Python when a
thread completes. _thread._set_sentinel() function creates a lock
which is released when the thread completes. It sets on_delete
callback to the internal release_sentinel() function. This lock is
known as Threading._tstate_lock in the threading module.
The release_sentinel() function uses the Python C API. The problem is
that on_delete is called late in the Python finalization, when the C
API is no longer fully working.
The PyThreadState_Clear() function now calls the
PyThreadState.on_delete callback. Previously, that happened in
PyThreadState_Delete().
The release_sentinel() function is now called when the C API is still
fully working.
Replace a few Py_FatalError() calls if tstate is NULL with
assert(tstate != NULL) in ceval.c.
PyEval_AcquireThread(), PyEval_ReleaseThread() and
PyEval_RestoreThread() must never be called with a NULL tstate.
* Add DICT_UPDATE and DICT_MERGE bytecodes. Use them for ** unpacking.
* Remove BUILD_MAP_UNPACK and BUILD_MAP_UNPACK_WITH_CALL, as they are now unused.
* Update magic number for ** unpacking opcodes.
* Update dis.rst to incorporate new bytecodes.
* Add blurb entry.
* Add three new bytecodes: LIST_TO_TUPLE, LIST_EXTEND, SET_UPDATE. Use them to implement star unpacking expressions.
* Remove four bytecodes BUILD_LIST_UNPACK, BUILD_TUPLE_UNPACK, BUILD_SET_UNPACK and BUILD_TUPLE_UNPACK_WITH_CALL opcodes as they are now unused.
* Update magic number and dis.rst for new bytecodes.
* bpo-39336: Allow setattr to fail on modules which aren't assignable
When attaching a child module to a package if the object in sys.modules raises an AttributeError (e.g. because it is immutable) it causes the whole import to fail. This now allows immutable packages to exist and an ImportWarning is reported and the AttributeError exception is ignored.
Python-ast.h contains a macro named Yield that conflicts with the Yield macro
in Windows system headers. While Python-ast.h has an "undef Yield" directive
to prevent this, it means that Python-ast.h must be included before Windows
header files or we run into a re-declaration warning. In commit c96be811fa
an include for pycore_pystate.h was added which indirectly includes Windows
header files. In this commit we re-order the includes to fix this warning.
* Reorder the __aenter__ and __aexit__ checks for async with
* Add assertions for async with body being skipped
* Swap __aexit__ and __aenter__ loading in the documentation
Break up COMPARE_OP into four logically distinct opcodes:
* COMPARE_OP for rich comparisons
* IS_OP for 'is' and 'is not' tests
* CONTAINS_OP for 'in' and 'is not' tests
* JUMP_IF_NOT_EXC_MATCH for checking exceptions in 'try-except' statements.
This adds a new function named _PyErr_GetExcInfo() that is a variation of the
original PyErr_GetExcInfo() taking a PyThreadState as its first argument.
That function allows to retrieve the exceptions information of any Python
thread -- not only the current one.
The fix changes copy_location() to require an extra node from which to extract the end location, and fixing all 5 call sites.
https://bugs.python.org/issue39235
