Check the empty list

deep_ep/buffer.py

@@ -290,7 +290,8 @@ class Buffer:
             recv_topk_idx: received expert indices.
             recv_topk_weights: received expert weights.
             num_recv_tokens_per_expert_list: Python list shaped `[num_local_experts]`, the received token count by
-                each local expert, aligned to the input `expert_alignment`.
+                each local expert, aligned to the input `expert_alignment`. If `num_worst_tokens` is specified, the list
+                will be empty.
             handle: the returned communication handle.
             event: the event after executing the kernel (valid only if `async_finish` is set).
         """

tests/test_intranode.py

@@ -117,9 +117,10 @@ def test_main(num_sms: int, local_rank: int, num_ranks: int, rank: int, buffer:
                     if with_topk:
                         num_worst_tokens = num_tokens * num_ranks
                         dispatch_args.update({'num_worst_tokens': num_worst_tokens})
-                        recv_worst_x, recv_worst_topk_idx, recv_worst_topk_weights, _, _, event = buffer.dispatch(**dispatch_args)
+                        recv_worst_x, recv_worst_topk_idx, recv_worst_topk_weights, empty_list, _, event = buffer.dispatch(**dispatch_args)
                         event.current_stream_wait() if async_mode else ()
                         recv_worst_x = per_token_cast_back(*recv_worst_x) if isinstance(recv_worst_x, tuple) else recv_worst_x
+                        assert len(empty_list) == 0
                         assert num_worst_tokens == recv_worst_x.size(0)
                         assert num_worst_tokens == recv_worst_topk_idx.size(0)
                         assert num_worst_tokens == recv_worst_topk_weights.size(0)