Changes pending from vllm-project/vllm#2976

Signed-off-by: Joe Runde <[email protected]>

vllm/engine/llm_engine.py

@@ -1013,12 +1013,15 @@ def _check_stop(self, seq: Sequence,
             if seq.output_text.endswith(stop_str):
                 self._finalize_sequence(seq, sampling_params, stop_str)
                 seq.status = SequenceStatus.FINISHED_STOPPED
+                seq.stop_reason = stop_str
                 return
-        if seq.get_last_token_id() in sampling_params.stop_token_ids:
+        last_token_id = seq.get_last_token_id()
+        if last_token_id in sampling_params.stop_token_ids:
             stop_str = self.get_tokenizer_for_seq(seq).convert_ids_to_tokens(
-                seq.get_last_token_id())
+                last_token_id)
             self._finalize_sequence(seq, sampling_params, stop_str)
             seq.status = SequenceStatus.FINISHED_STOPPED
+            seq.stop_reason = last_token_id
             return
 
         # Check if the sequence has generated the EOS token.

vllm/entrypoints/openai/protocol.py

@@ -254,6 +254,7 @@ class CompletionResponseChoice(BaseModel):
     text: str
     logprobs: Optional[LogProbs] = None
     finish_reason: Optional[Literal["stop", "length"]] = None
+    stop_reason: Union[None, int, str] = None
 
 
 class CompletionResponse(BaseModel):
@@ -270,6 +271,7 @@ class CompletionResponseStreamChoice(BaseModel):
     text: str
     logprobs: Optional[LogProbs] = None
     finish_reason: Optional[Literal["stop", "length"]] = None
+    stop_reason: Union[None, int, str] = None
 
 
 class CompletionStreamResponse(BaseModel):
@@ -291,6 +293,7 @@ class ChatCompletionResponseChoice(BaseModel):
     message: ChatMessage
     logprobs: Optional[LogProbs] = None
     finish_reason: Optional[Literal["stop", "length"]] = None
+    stop_reason: Union[None, int, str] = None
 
 
 class ChatCompletionResponse(BaseModel):
@@ -312,6 +315,7 @@ class ChatCompletionResponseStreamChoice(BaseModel):
     delta: DeltaMessage
     logprobs: Optional[LogProbs] = None
     finish_reason: Optional[Literal["stop", "length"]] = None
+    stop_reason: Union[None, int, str] = None
 
 
 class ChatCompletionStreamResponse(BaseModel):

vllm/entrypoints/openai/serving_chat.py

@@ -213,7 +213,8 @@ async def chat_completion_stream_generator(
                             index=i,
                             delta=DeltaMessage(content=delta_text),
                             logprobs=logprobs,
-                            finish_reason=output.finish_reason)
+                            finish_reason=output.finish_reason,
+                            stop_reason=output.stop_reason)
                         chunk = ChatCompletionStreamResponse(
                             id=request_id,
                             object=chunk_object_type,
@@ -271,6 +272,7 @@ async def chat_completion_full_generator(
                 message=ChatMessage(role=role, content=output.text),
                 logprobs=logprobs,
                 finish_reason=output.finish_reason,
+                stop_reason=output.stop_reason,
             )
             choices.append(choice_data)
 

vllm/entrypoints/openai/serving_completion.py

@@ -261,6 +261,7 @@ async def completion_stream_generator(
                     previous_texts[i] = output.text
                     previous_num_tokens[i] = len(output.token_ids)
                     finish_reason = output.finish_reason
+                    stop_reason = output.stop_reason
                     response_json = CompletionStreamResponse(
                         id=request_id,
                         created=created_time,
@@ -271,6 +272,7 @@ async def completion_stream_generator(
                                 text=delta_text,
                                 logprobs=logprobs,
                                 finish_reason=finish_reason,
+                                stop_reason=stop_reason,
                             )
                         ]).model_dump_json()
                     yield f"data: {response_json}\n\n"
@@ -295,6 +297,7 @@ async def completion_stream_generator(
                                     text="",
                                     logprobs=logprobs,
                                     finish_reason=output.finish_reason,
+                                    stop_reason=output.stop_reason,
                                 )
                             ],
                             usage=final_usage,
@@ -354,6 +357,7 @@ def request_output_to_completion_response(
                     text=output_text,
                     logprobs=logprobs,
                     finish_reason=output.finish_reason,
+                    stop_reason=output.stop_reason,
                 )
                 choices.append(choice_data)
 

vllm/outputs.py

@@ -1,4 +1,4 @@
-from typing import List, Optional
+from typing import List, Optional, Union
 import time
 
 from vllm.sequence import (PromptLogprobs, SampleLogprobs, SequenceGroup,
@@ -18,6 +18,9 @@ class CompletionOutput:
         logprobs: The log probabilities of the top probability words at each
             position if the logprobs are requested.
         finish_reason: The reason why the sequence is finished.
+        stop_reason: The stop string or token id that caused the completion to stop,
+            None if the completion finished for some other reason including
+            encountering the EOS token.
         lora_request: The LoRA request that was used to generate the output.
     """
 
@@ -29,6 +32,7 @@ def __init__(
         cumulative_logprob: float,
         logprobs: Optional[SampleLogprobs],
         finish_reason: Optional[str] = None,
+        stop_reason: Union[int, str, None] = None,
         lora_request: Optional[LoRARequest] = None,
     ) -> None:
         self.index = index
@@ -37,6 +41,7 @@ def __init__(
         self.cumulative_logprob = cumulative_logprob
         self.logprobs = logprobs
         self.finish_reason = finish_reason
+        self.stop_reason = stop_reason
         self.lora_request = lora_request
 
     def finished(self) -> bool:
@@ -48,7 +53,8 @@ def __repr__(self) -> str:
                 f"token_ids={self.token_ids}, "
                 f"cumulative_logprob={self.cumulative_logprob}, "
                 f"logprobs={self.logprobs}, "
-                f"finish_reason={self.finish_reason})")
+                f"finish_reason={self.finish_reason}, "
+                f"stop_reason={self.stop_reason})")
 
 
 class RequestOutput:
@@ -111,7 +117,8 @@ def from_seq_group(cls, seq_group: SequenceGroup) -> "RequestOutput":
                              seq.get_output_token_ids(),
                              seq.get_cumulative_logprob(),
                              seq.output_logprobs if include_logprobs else None,
-                             SequenceStatus.get_finished_reason(seq.status))
+                             SequenceStatus.get_finished_reason(seq.status),
+                             seq.stop_reason)
             for seq in top_n_seqs
         ]
 

vllm/sequence.py

@@ -159,6 +159,7 @@ def __init__(
         # Initialize the logical token blocks with the prompt token ids.
         self._append_tokens_to_blocks(prompt_token_ids)
         self.status = SequenceStatus.WAITING
+        self.stop_reason: Union[int, str, None] = None
 
         # Used for incremental detokenization
         self.prefix_offset = 0