[enhancement](errormsg) print backend ip when brpc light pool is full (…

…#42370)

## Proposed changes

Issue Number: close #xxx

<!--Describe your changes.-->

Co-authored-by: yiguolei <[email protected]>

be/src/service/internal_service.cpp

@@ -178,9 +178,13 @@ concept CanCancel = requires(T* response) { response->mutable_status(); };
 template <CanCancel T>
 void offer_failed(T* response, google::protobuf::Closure* done, const FifoThreadPool& pool) {
     brpc::ClosureGuard closure_guard(done);
-    response->mutable_status()->set_status_code(TStatusCode::CANCELLED);
-    response->mutable_status()->add_error_msgs("fail to offer request to the work pool, pool=" +
-                                               pool.get_info());
+    // Should use status to generate protobuf message, because it will encoding Backend Info
+    // into the error message and then we could know which backend's pool is full.
+    Status st = Status::Error<TStatusCode::CANCELLED>(
+            "fail to offer request to the work pool, pool={}", pool.get_info());
+    st.to_protobuf(response->mutable_status());
+    LOG(WARNING) << "cancelled due to fail to offer request to the work pool, pool="
+                 << pool.get_info();
 }
 
 template <typename T>