Revert "[user-streams] Make device-agnostic streams weakref compatible (pytorch#164304)"

This reverts commit bfc2050.

Reverted pytorch#164304 on behalf of https://github.com/atalman due to Breaks periodic: test/dynamo/test_streams.py::TestStreams::test_stream_weakref [GH job link](https://github.com/pytorch/pytorch/actions/runs/18909552619/job/53979171605) [HUD commit link](https://hud.pytorch.org/pytorch/pytorch/commit/cde81e92b95eee9af2879c9c75f7b03699ca72ad) ([comment](pytorch#164304 (comment)))

Author: pytorchmergebot

test/dynamo/test_streams.py

@@ -1,5 +1,4 @@
 # Owner(s): ["module: dynamo"]
-import weakref
 
 import torch
 import torch._dynamo.test_case
@@ -16,10 +15,6 @@ def setUpClass(cls):
     def tearDownClass(cls):
         super().tearDownClass()
 
-    def test_stream_weakref(self):
-        s = torch.Stream()
-        weakref.ref(s)
-
     @requires_cuda
     def test_run_opcheck(self):
         from torch._dynamo.variables.streams import fork_stream, join_stream

torch/csrc/Stream.cpp

@@ -95,7 +95,6 @@ static PyObject* THPStream_pynew(
   self->device_index = static_cast<int64_t>(stream_opt->device_index());
   self->device_type = static_cast<int64_t>(stream_opt->device_type());
   self->context = nullptr;
-  self->weakreflist = nullptr;
 
   return static_cast<PyObject*>(ptr.release());
   END_HANDLE_TH_ERRORS
@@ -115,13 +114,11 @@ PyObject* THPStream_Wrap(const c10::Stream& stream) {
   self->device_index = static_cast<int64_t>(stream.device_index());
   self->device_type = static_cast<int64_t>(stream.device_type());
   self->context = nullptr;
-  self->weakreflist = nullptr;
   return ptr.release();
   END_HANDLE_TH_ERRORS
 }
 
 static void THPStream_dealloc(THPStream* self) {
-  PyObject_ClearWeakRefs((PyObject*)self);
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
@@ -447,7 +444,7 @@ static PyTypeObject THPStreamType = {
     nullptr, /* tp_traverse */
     nullptr, /* tp_clear */
     THPStream_richcompare, /* tp_richcompare */
-    offsetof(THPStream, weakreflist), /* tp_weaklistoffset */
+    0, /* tp_weaklistoffset */
     nullptr, /* tp_iter */
     nullptr, /* tp_iternext */
     // NOLINTNEXTLINE(*const-cast)

torch/csrc/Stream.h

@@ -13,7 +13,6 @@ struct THPStream {
   int64_t device_index;
   // Used to switch stream context management, initialized lazily.
   PyObject* context;
-  PyObject* weakreflist;
 };
 extern TORCH_API PyTypeObject* THPStreamClass;