[Refactor]: clean up diffusion worker interfaces (#5217)

Signed-off-by: Huang, Zeyu <11222265+fhfuih@users.noreply.github.com>
Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/diffusion/test_multiproc_engine_concurrency.py

@@ -526,7 +526,7 @@ class TestWorkerProcRpcRankStatus:
 
         monkeypatch.setattr(torch.distributed, "all_gather_object", _all_gather_object)
 
-        result, should_reply = proc.execute_rpc(
+        result, should_reply = proc._execute_rpc(
             {
                 "method": "remove_lora",
                 "args": (),
@@ -549,7 +549,7 @@ class TestWorkerProcRpcRankStatus:
         proc.worker.execute_method = Mock(side_effect=RuntimeError("local boom"))
         monkeypatch.setattr(torch.distributed, "is_initialized", lambda: False)
 
-        result, should_reply = proc.execute_rpc(
+        result, should_reply = proc._execute_rpc(
             {
                 "method": "add_lora",
                 "args": (),
@@ -575,7 +575,7 @@ class TestWorkerProcRpcRankStatus:
         proc = self._make_worker_proc()
 
         with pytest.raises(ValueError, match="collect_rank_status requires exec_all_ranks=True"):
-            proc.execute_rpc(
+            proc._execute_rpc(
                 {
                     "method": "ping",
                     "args": (),
@@ -594,7 +594,7 @@ class TestWorkerProcRpcRankStatus:
         proc.worker.execute_method = Mock(side_effect=original)
 
         with pytest.raises(ValueError) as excinfo:
-            proc.execute_rpc(
+            proc._execute_rpc(
                 {
                     "method": "bad",
                     "args": (),