[tokenizer] Surface scheduler load info (num_running_reqs / num_waiting_reqs) in meta_info (#24000)

python/sglang/srt/managers/tokenizer_manager.py

@@ -1749,6 +1749,19 @@ class TokenizerManager(TokenizerControlMixin, TokenizerManagerScoreMixin):
                 "num_retractions": recv_obj.retraction_counts[i],
             }
 
+            # Surface scheduler load info on each response so clients can do
+            # response-based flow control without polling /v1/loads. The
+            # scheduler already piggy-backs the per-DP-rank load on
+            # BatchStrOutput / BatchTokenIDOutput via the ``load`` field.
+            load = getattr(recv_obj, "load", None)
+            if load is not None:
+                num_running_reqs = getattr(load, "num_running_reqs", None)
+                num_waiting_reqs = getattr(load, "num_waiting_reqs", None)
+                if num_running_reqs is not None:
+                    meta_info["num_running_reqs"] = num_running_reqs
+                if num_waiting_reqs is not None:
+                    meta_info["num_waiting_reqs"] = num_waiting_reqs
+
             if self.enable_metrics:
                 if recv_obj.time_stats is not None:
                     scheduler_time_stats = recv_obj.time_stats[i]