Fix stuck in `get_new_prefill_batch` (#948)

python/sglang/srt/managers/tp_worker.py

@@ -364,12 +364,13 @@ class ModelTpServer:
         # Compute matched prefix length
         for req in self.waiting_queue:
             req.input_ids = req.origin_input_ids + req.output_ids
+            try_match_ids = req.input_ids
+            if req.return_logprob:
+                try_match_ids = req.input_ids[: req.logprob_start_len]
+            # NOTE: the prefix_indices must always be aligned with last_node
             prefix_indices, last_node = self.tree_cache.match_prefix(
-                rid=req.rid,
-                key=req.input_ids,
+                rid=req.rid, key=try_match_ids
             )
-            if req.return_logprob:
-                prefix_indices = prefix_indices[: req.logprob_start_len]
             req.extend_input_len = len(req.input_ids) - len(prefix_indices)
             req.prefix_indices = prefix_indices
             req.last_node = last_node