faulthandler now works in non-Python threads

Issue #26563:

* Add _PyGILState_GetInterpreterStateUnsafe() function: the single
  PyInterpreterState used by this process' GILState implementation.
* Enhance _Py_DumpTracebackThreads() to retrieve the interpreter state from
  autoInterpreterState in last resort. The function now accepts NULL for interp
  and current_tstate parameters.
* test_faulthandler: fix a ResourceWarning when test is interrupted by CTRL+c

2 files changed, 29 insertions, 8 deletions

diff --git a/Include/pystate.h b/Include/pystate.h
index 550c332..9423bc7 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -243,15 +243,23 @@ PyAPI_FUNC(void) PyGILState_Release(PyGILState_STATE);
 */
 PyAPI_FUNC(PyThreadState *) PyGILState_GetThisThreadState(void);
 
-/* Helper/diagnostic function - return 1 if the current thread
- * currently holds the GIL, 0 otherwise
- */
 #ifndef Py_LIMITED_API
 /* Issue #26558: Flag to disable PyGILState_Check().
-   If set, PyGILState_Check() always return 1. */
+   If set to non-zero, PyGILState_Check() always return 1. */
 PyAPI_DATA(int) _PyGILState_check_enabled;
 
+/* Helper/diagnostic function - return 1 if the current thread
+   currently holds the GIL, 0 otherwise.
+
+   The function returns 1 if _PyGILState_check_enabled is non-zero. */
 PyAPI_FUNC(int) PyGILState_Check(void);
+
+/* Unsafe function to get the single PyInterpreterState used by this process'
+   GILState implementation.
+
+   Return NULL before _PyGILState_Init() is called and after _PyGILState_Fini()
+   is called. */
+PyAPI_FUNC(PyInterpreterState *) _PyGILState_GetInterpreterStateUnsafe(void);
 #endif
 
 #endif   /* #ifdef WITH_THREAD */
diff --git a/Include/traceback.h b/Include/traceback.h
index 7c630e3..76e169a 100644
--- a/Include/traceback.h
+++ b/Include/traceback.h
@@ -53,19 +53,32 @@ PyAPI_DATA(void) _Py_DumpTraceback(
     PyThreadState *tstate);
 
 /* Write the traceback of all threads into the file 'fd'. current_thread can be
-   NULL. Return NULL on success, or an error message on error.
+   NULL.
+
+   Return NULL on success, or an error message on error.
 
    This function is written for debug purpose only. It calls
    _Py_DumpTraceback() for each thread, and so has the same limitations. It
    only write the traceback of the first 100 threads: write "..." if there are
    more threads.
 
+   If current_tstate is NULL, the function tries to get the Python thread state
+   of the current thread. It is not an error if the function is unable to get
+   the current Python thread state.
+
+   If interp is NULL, the function tries to get the interpreter state from
+   the current Python thread state, or from
+   _PyGILState_GetInterpreterStateUnsafe() in last resort.
+
+   It is better to pass NULL to interp and current_tstate, the function tries
+   different options to retrieve these informations.
+
    This function is signal safe. */
 
 PyAPI_DATA(const char*) _Py_DumpTracebackThreads(
-    int fd, PyInterpreterState *interp,
-    PyThreadState *current_thread);
-
+    int fd,
+    PyInterpreterState *interp,
+    PyThreadState *current_tstate);
 
 #ifndef Py_LIMITED_API