diff --git a/python/sglang/bench_serving.py b/python/sglang/bench_serving.py
index dd5aeccb0..1624aaacc 100644
--- a/python/sglang/bench_serving.py
+++ b/python/sglang/bench_serving.py
@@ -73,6 +73,12 @@ class RequestFuncOutput:
     error: str = ""
     output_len: int = 0
 
+    @staticmethod
+    def init_new(request_func_input: RequestFuncInput):
+        output = RequestFuncOutput()
+        output.prompt_len = request_func_input.prompt_len
+        return output
+
 
 def remove_prefix(text: str, prefix: str) -> str:
     return text[len(prefix) :] if text.startswith(prefix) else text
@@ -114,8 +120,7 @@ async def async_request_trt_llm(
         if args.disable_ignore_eos:
             del payload["min_length"]
             del payload["end_id"]
-        output = RequestFuncOutput()
-        output.prompt_len = request_func_input.prompt_len
+        output = RequestFuncOutput.init_new(request_func_input)
 
         ttft = 0.0
         st = time.perf_counter()
@@ -186,8 +191,7 @@ async def async_request_openai_completions(
         }
         headers = get_auth_headers()
 
-        output = RequestFuncOutput()
-        output.prompt_len = request_func_input.prompt_len
+        output = RequestFuncOutput.init_new(request_func_input)
 
         generated_text = ""
         output_len = request_func_input.output_len
@@ -269,8 +273,7 @@ async def async_request_truss(
         }
         headers = get_auth_headers()
 
-        output = RequestFuncOutput()
-        output.prompt_len = request_func_input.prompt_len
+        output = RequestFuncOutput.init_new(request_func_input)
 
         generated_text = ""
         ttft = 0.0
@@ -355,8 +358,7 @@ async def async_request_sglang_generate(
 
         headers = get_auth_headers()
 
-        output = RequestFuncOutput()
-        output.prompt_len = request_func_input.prompt_len
+        output = RequestFuncOutput.init_new(request_func_input)
 
         generated_text = ""
         output_len = request_func_input.output_len