Atan Bhardwaj modernized core components in the grpc/grpc and protocolbuffers/protobuf repositories, focusing on performance and maintainability. He refactored proto_reflection_descriptor_database to use absl::flat_hash_map and absl::flat_hash_set, optimizing descriptor lookups and reducing memory churn. In protocolbuffers/protobuf, he migrated DescriptorDatabase to absl::string_view, streamlining string handling and removing legacy code. These changes, implemented in C++ with an emphasis on data structures and code refactoring, improved API clarity and future-proofed the codebase. Atan’s work aligned modernization patterns across both repositories, enabling consistent performance improvements and simplifying ongoing software maintenance without introducing new bugs during the development period.