fix #4335

Former-commit-id: 2ab449adbb160f339a0586edeb846fa311ad8382

src/llamafactory/chat/hf_engine.py

@@ -59,6 +59,7 @@ class HuggingfaceEngine(BaseEngine):
             self.tokenizer, model_args, finetuning_args, is_trainable=False, add_valuehead=(not self.can_generate)
         )  # must after fixing tokenizer to resize vocab
         self.generating_args = generating_args.to_dict()
+        self.semaphore = asyncio.Semaphore(int(os.environ.get("MAX_CONCURRENT", "1")))
 
     @staticmethod
     def _process_args(
@@ -259,9 +260,6 @@ class HuggingfaceEngine(BaseEngine):
 
         return scores
 
-    async def start(self) -> None:
-        self._semaphore = asyncio.Semaphore(int(os.environ.get("MAX_CONCURRENT", 1)))
-
     async def chat(
         self,
         messages: Sequence[Dict[str, str]],
@@ -286,7 +284,7 @@ class HuggingfaceEngine(BaseEngine):
             image,
             input_kwargs,
         )
-        async with self._semaphore:
+        async with self.semaphore:
             with concurrent.futures.ThreadPoolExecutor() as pool:
                 return await loop.run_in_executor(pool, self._chat, *input_args)
 
@@ -314,7 +312,7 @@ class HuggingfaceEngine(BaseEngine):
             image,
             input_kwargs,
         )
-        async with self._semaphore:
+        async with self.semaphore:
             with concurrent.futures.ThreadPoolExecutor() as pool:
                 stream = self._stream_chat(*input_args)
                 while True:
@@ -333,6 +331,6 @@ class HuggingfaceEngine(BaseEngine):
 
         loop = asyncio.get_running_loop()
         input_args = (self.model, self.tokenizer, batch_input, input_kwargs)
-        async with self._semaphore:
+        async with self.semaphore:
             with concurrent.futures.ThreadPoolExecutor() as pool:
                 return await loop.run_in_executor(pool, self._get_scores, *input_args)