Issue #19787: PyThread_set_key_value() now always set the value

In Python 3.3, PyThread_set_key_value() did nothing if the key already exists
(if the current value is a non-NULL pointer).

When _PyGILState_NoteThreadState() is called twice on the same thread with a
different Python thread state, it still keeps the old Python thread state to
keep the old behaviour. Replacing the Python thread state with the new state
introduces new bugs: see issues #10915 and #15751.

1 files changed, 3 insertions, 6 deletions

diff --git a/Modules/_tracemalloc.c b/Modules/_tracemalloc.c
index b39e950..95b05d6 100644
--- a/Modules/_tracemalloc.c
+++ b/Modules/_tracemalloc.c
@@ -168,14 +168,11 @@ set_reentrant(int reentrant)
     assert(reentrant == 0 || reentrant == 1);
     if (reentrant) {
         assert(PyThread_get_key_value(tracemalloc_reentrant_key) == NULL);
-        PyThread_set_key_value(tracemalloc_reentrant_key,
-                               REENTRANT);
+        PyThread_set_key_value(tracemalloc_reentrant_key, REENTRANT);
     }
     else {
-        /* FIXME: PyThread_set_key_value() cannot be used to set the flag
-           to zero, because it does nothing if the variable has already
-           a value set. */
-        PyThread_delete_key_value(tracemalloc_reentrant_key);
+        assert(PyThread_get_key_value(tracemalloc_reentrant_key) == REENTRANT);
+        PyThread_set_key_value(tracemalloc_reentrant_key, NULL);
     }
 }