Add a new test and fix some assertion failures.

Author: ZeroIntensity

Lib/test/test_interpreters/test_api.py

@@ -2362,14 +2362,17 @@ def test_set___main___attrs(self):
 
 
 class TestSharedObjectProxy(TestBase):
-    def unshareable(self, file=os.devnull):
+    def unshareable(self, file=None):
         class Unshareable:
             def __init__(self):
-                # This prevents the object from being pickleable
-                self.file = open(file, "w+")
+                self.file = file
+                # Prevents the object from being pickleable
+                self._dummy = open(os.devnull)
 
             def __del__(self):
-                self.file.close()
+                self._dummy.close()
+                if self.file:
+                    self.file.write("done")
 
             def foo(self):
                 return 42
@@ -2401,6 +2404,23 @@ def get_interp(obj):
         finally:
             interp.close()
 
+    def test_object_collected_after_proxy_closes(self):
+        import io
+
+        buffer = io.StringIO()
+        interp = interpreters.create()
+        try:
+            def write_to_proxy(obj):
+                obj.file.write("hello")
+
+            with interpreters.share(self.unshareable(buffer)) as proxy:
+                self.assertFalse(is_pickleable(proxy))
+                self.assertIsNone(interp.call(write_to_proxy, proxy))
+
+            self.assertEqual(buffer.getvalue(), "hellodone")
+        finally:
+            interp.close()
+
 
 
 if __name__ == '__main__':

Modules/_interpretersmodule.c

@@ -849,6 +849,7 @@ _sharedobjectproxy_freelist_push(PyObject *mod, SharedObjectProxy *self)
 {
     module_state *state = get_module_state(mod);
     assert(state != NULL);
+    assert(self->previous == NULL);
 
     // XXX Make an FT wrapper?
 #ifdef Py_GIL_DISABLED
@@ -872,11 +873,10 @@ _sharedobjectproxy_freelist_pop(PyObject *mod)
 #else
     PyObject *top = state->available_proxies;
 #endif
-    FT_ATOMIC_STORE_PTR_RELAXED(state->available_proxies,
-                                top == NULL
-                                ? NULL
-                                : (PyObject *)SharedObjectProxy_CAST(top)->next);
-
+    if (top != NULL) {
+        FT_ATOMIC_STORE_PTR_RELAXED(state->available_proxies, (PyObject *)SharedObjectProxy_CAST(top)->next);
+        SharedObjectProxy_CAST(top)->next = NULL;
+    }
     return (SharedObjectProxy *)top;
 }
 
@@ -897,6 +897,9 @@ _sharedobjectproxy_detach(PyObject *mod, SharedObjectProxy *self)
         return -1;
     }
 
+    // In the freelist, we don't use a doubly linked list.
+    self->context_id = -1;
+    self->previous = NULL;
     _sharedobjectproxy_freelist_push(mod, self);
     return 0;
 }