gh-140936: Fix JIT assertion crash at finalization if some generator is alive (GH-140969)

Lib/test/test_capi/test_opt.py

@@ -2660,6 +2660,25 @@ def f():
 
         f()
 
+    def test_interpreter_finalization_with_generator_alive(self):
+        script_helper.assert_python_ok("-c", textwrap.dedent("""
+            import sys
+            t = tuple(range(%d))
+            def simple_for():
+                for x in t:
+                    x
+
+            def gen():
+                try:
+                    yield
+                except:
+                    simple_for()
+
+            sys.settrace(lambda *args: None)
+            simple_for()
+            g = gen()
+            next(g)
+        """ % _testinternalcapi.SPECIALIZATION_THRESHOLD))
 
 
 def global_identity(x):

Python/optimizer.c

@@ -118,7 +118,13 @@ _PyOptimizer_Optimize(
 {
     _PyStackRef *stack_pointer = frame->stackpointer;
     PyInterpreterState *interp = _PyInterpreterState_GET();
-    assert(interp->jit);
+    if (!interp->jit) {
+        // gh-140936: It is possible that interp->jit will become false during
+        // interpreter finalization. However, the specialized JUMP_BACKWARD_JIT
+        // instruction may still be present. In this case, we should
+        // return immediately without optimization.
+        return 0;
+    }
     assert(!interp->compiling);
 #ifndef Py_GIL_DISABLED
     interp->compiling = true;