1 files changed, 20 insertions, 0 deletions
diff --git a/Python/lock.c b/Python/lock.c
index ea6ac00bfec..a49d587a168 100644
--- a/Python/lock.c
+++ b/Python/lock.c
@@ -95,6 +95,18 @@ _PyMutex_LockTimed(PyMutex *m, PyTime_t timeout, _PyLockFlags flags)
         if (timeout == 0) {
             return PY_LOCK_FAILURE;
         }
+        if ((flags & _PY_LOCK_PYTHONLOCK) && Py_IsFinalizing()) {
+            // At this phase of runtime shutdown, only the finalization thread
+            // can have attached thread state; others hang if they try
+            // attaching. And since operations on this lock requires attached
+            // thread state (_PY_LOCK_PYTHONLOCK), the finalization thread is
+            // running this code, and no other thread can unlock.
+            // Raise rather than hang. (_PY_LOCK_PYTHONLOCK allows raising
+            // exceptons.)
+            PyErr_SetString(PyExc_PythonFinalizationError,
+                            "cannot acquire lock at interpreter finalization");
+            return PY_LOCK_FAILURE;
+        }
 
         uint8_t newv = v;
         if (!(v & _Py_HAS_PARKED)) {
@@ -622,3 +634,11 @@ PyMutex_Unlock(PyMutex *m)
         Py_FatalError("unlocking mutex that is not locked");
     }
 }
+
+
+#undef PyMutex_IsLocked
+int
+PyMutex_IsLocked(PyMutex *m)
+{
+    return _PyMutex_IsLocked(m);
+}