Add image_token in conversation.py (#1632)

Co-authored-by: yizhang2077 <1109276519@qq.com>

python/sglang/srt/conversation.py

@@ -70,6 +70,9 @@ class Conversation:
     sep2: str = None
     # Stop criteria (the default one is EOS token)
     stop_str: Union[str, List[str]] = None
+    # The string that represents an image token in the prompt
+    image_token: str = "<image>"
+
     image_data: Optional[List[str]] = None
     modalities: Optional[List[str]] = None
 
@@ -334,6 +337,7 @@ def copy(self):
             sep=self.sep,
             sep2=self.sep2,
             stop_str=self.stop_str,
+            image_token=self.image_token,
         )
 
     def dict(self):
@@ -381,6 +385,7 @@ def generate_chat_conv(
         stop_str=conv.stop_str,
         image_data=[],
         modalities=[],
+        image_token=conv.image_token,
     )
 
     if isinstance(request.messages, str):
@@ -412,9 +417,13 @@ def generate_chat_conv(
                         num_image_url += 1
                         conv.modalities.append(content.modalities)
                 if num_image_url > 1:
-                    image_token = "<image>"
+                    image_token = conv.image_token
                 else:
-                    image_token = "<image>\n"
+                    image_token = (
+                        conv.image_token + "\n"
+                        if conv.name != "qwen2-vl"
+                        else conv.image_token
+                    )
                 for content in message.content:
                     if content.type == "text":
                         if num_image_url > 16:

python/sglang/srt/openai_api/adapter.py

@@ -117,7 +117,9 @@ def create_streaming_error_response(
 def load_chat_template_for_openai_api(tokenizer_manager, chat_template_arg):
     global chat_template_name
 
-    logger.info(f"Use chat template: {chat_template_arg}")
+    logger.info(
+        f"Use chat template for the OpenAI-compatible API server: {chat_template_arg}"
+    )
     if not chat_template_exists(chat_template_arg):
         if not os.path.exists(chat_template_arg):
             raise RuntimeError(