diff --git a/xllm/api_service/api_service.cpp b/xllm/api_service/api_service.cpp
old mode 100644
new mode 100755
index 69441f26..204b9f90
--- a/xllm/api_service/api_service.cpp
+++ b/xllm/api_service/api_service.cpp
@@ -146,8 +146,8 @@ void ChatCompletionsImpl(std::unique_ptr<Service>& service,
     return;
   }
 
-  auto call =
-      std::make_shared<ChatCall>(ctrl, guard.release(), req_pb, resp_pb);
+  auto call = std::make_shared<ChatCall>(
+      ctrl, guard.release(), req_pb, resp_pb, arena != nullptr /*use_arena*/);
   service->process_async(call);
 }
 }  // namespace
@@ -166,17 +166,18 @@ void APIService::ChatCompletionsHttp(
     return;
   }
 
-  auto arena = response->GetArena();
   auto ctrl = reinterpret_cast<brpc::Controller*>(controller);
 
   if (FLAGS_backend == "llm") {
+    auto arena = response->GetArena();
     CHECK(chat_service_impl_) << " chat service is invalid.";
     ChatCompletionsImpl<ChatCall, ChatServiceImpl>(
         chat_service_impl_, done_guard, arena, ctrl);
   } else if (FLAGS_backend == "vlm") {
     CHECK(mm_chat_service_impl_) << " mm chat service is invalid.";
+    // TODO: fix me - temporarily using heap allocation instead of arena
     ChatCompletionsImpl<MMChatCall, MMChatServiceImpl>(
-        mm_chat_service_impl_, done_guard, arena, ctrl);
+        mm_chat_service_impl_, done_guard, nullptr, ctrl);
   }
 }
 
diff --git a/xllm/api_service/stream_call.h b/xllm/api_service/stream_call.h
old mode 100644
new mode 100755
index 15124cc3..34f763fd
--- a/xllm/api_service/stream_call.h
+++ b/xllm/api_service/stream_call.h
@@ -39,8 +39,13 @@ class StreamCall : public Call {
   StreamCall(brpc::Controller* controller,
              ::google::protobuf::Closure* done,
              Request* request,
-             Response* response)
-      : Call(controller), done_(done), request_(request), response_(response) {
+             Response* response,
+             bool use_arena = true)
+      : Call(controller),
+        done_(done),
+        request_(request),
+        response_(response),
+        use_arena_(use_arena) {
     stream_ = request_->stream();
     if (stream_) {
       pa_ = controller_->CreateProgressiveAttachment();
@@ -67,6 +72,10 @@ class StreamCall : public Call {
     if (!stream_) {
       done_->Run();
     }
+    if (!use_arena_) {
+      delete request_;
+      delete response_;
+    }
   }
 
   bool write_and_finish(Response& response) {
@@ -142,6 +151,7 @@ class StreamCall : public Call {
   Response* response_;
 
   bool stream_ = false;
+  bool use_arena_ = true;
   butil::intrusive_ptr<brpc::ProgressiveAttachment> pa_;
   butil::IOBuf io_buf_;