bpo-36356: Destroy the GIL at exit (GH-12453)

* Add _PyEval_FiniThreads2(). _PyEval_FiniThreads() now only clears
  the pending lock, whereas _PyEval_FiniThreads2() destroys the GIL.
* pymain_free() now calls _PyEval_FiniThreads2().
* Py_FinalizeEx() now calls _PyEval_FiniThreads().

2 files changed, 17 insertions, 10 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index ccd0427..5480fba 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -188,20 +188,26 @@ PyEval_InitThreads(void)
     }
 }
 
+
 void
 _PyEval_FiniThreads(void)
 {
+    if (_PyRuntime.ceval.pending.lock != NULL) {
+        PyThread_free_lock(_PyRuntime.ceval.pending.lock);
+        _PyRuntime.ceval.pending.lock = NULL;
+    }
+}
+
+
+void
+_PyEval_FiniThreads2(void)
+{
     if (!gil_created()) {
         return;
     }
 
     destroy_gil();
     assert(!gil_created());
-
-    if (_PyRuntime.ceval.pending.lock != NULL) {
-        PyThread_free_lock(_PyRuntime.ceval.pending.lock);
-        _PyRuntime.ceval.pending.lock = NULL;
-    }
 }
 
 static inline void
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index d93fe06..0836e18 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -4,8 +4,9 @@
 
 #include "Python-ast.h"
 #undef Yield   /* undefine macro conflicting with <winbase.h> */
-#include "pycore_coreconfig.h"
+#include "pycore_ceval.h"   /* _PyEval_FiniThreads() */
 #include "pycore_context.h"
+#include "pycore_coreconfig.h"
 #include "pycore_fileutils.h"
 #include "pycore_hamt.h"
 #include "pycore_pathconfig.h"
@@ -555,12 +556,11 @@ pycore_create_interpreter(_PyRuntimeState *runtime,
         return _Py_INIT_ERR("can't make first thread");
     (void) PyThreadState_Swap(tstate);
 
-    /* We can't call _PyEval_FiniThreads() in Py_FinalizeEx because
-       destroying the GIL might fail when it is being referenced from
-       another running thread (see issue #9901).
+    /* Destroying the GIL in Py_FinalizeEx might fail when it is being
+       referenced from another running thread (see bpo-9901).
        Instead we destroy the previously created GIL here, which ensures
        that we can call Py_Initialize / Py_FinalizeEx multiple times. */
-    _PyEval_FiniThreads();
+    _PyEval_FiniThreads2();
 
     /* Auto-thread-state API */
     _PyGILState_Init(runtime, interp, tstate);
@@ -1357,6 +1357,7 @@ Py_FinalizeEx(void)
 
     call_ll_exitfuncs(runtime);
 
+    _PyEval_FiniThreads();
     _PyRuntime_Finalize();
     return status;
 }