[Frontend] Fix request length check and add option to disallow auto truncation in scheduler (#2876)

python/sglang/srt/managers/scheduler.py

@@ -78,6 +78,7 @@ from sglang.srt.managers.schedule_policy import (
 from sglang.srt.managers.session_controller import Session
 from sglang.srt.managers.tp_worker import TpModelWorker
 from sglang.srt.managers.tp_worker_overlap_thread import TpModelWorkerClient
+from sglang.srt.managers.utils import validate_input_length
 from sglang.srt.mem_cache.chunk_cache import ChunkCache
 from sglang.srt.mem_cache.radix_cache import RadixCache
 from sglang.srt.metrics.collector import SchedulerMetricsCollector, SchedulerStats
@@ -690,14 +691,16 @@ class Scheduler:
             # By default, only return the logprobs for output tokens
             req.logprob_start_len = len(req.origin_input_ids) - 1
 
-        # Truncate prompts that are too long
-        if len(req.origin_input_ids) > self.max_req_input_len:
-            logger.warning(
-                "Request length is longer than the KV cache pool size or "
-                "the max context length. Truncated. "
-                f"{len(req.origin_input_ids)=}, {self.max_req_input_len=}."
-            )
-            req.origin_input_ids = req.origin_input_ids[: self.max_req_input_len]
+        # Validate prompts length
+        error_msg = validate_input_length(
+            req,
+            self.max_req_input_len,
+            self.server_args.allow_auto_truncate,
+        )
+
+        if error_msg:
+            self.waiting_queue.append(req)
+            return
 
         req.sampling_params.max_new_tokens = min(
             (
@@ -745,13 +748,12 @@ class Scheduler:
         )
         req.tokenizer = self.tokenizer
 
-        # Truncate prompts that are too long
-        if len(req.origin_input_ids) >= self.max_req_input_len:
-            logger.warning(
-                "Request length is longer than the KV cache pool size or "
-                "the max context length. Truncated!!!"
-            )
-            req.origin_input_ids = req.origin_input_ids[: self.max_req_input_len]
+        # Validate prompts length
+        validate_input_length(
+            req,
+            self.max_req_input_len,
+            self.server_args.allow_auto_truncate,
+        )
 
         self.waiting_queue.append(req)