Samuel Zhang Email & Phone Number

San Francisco, California, Us

 Working as Backend/Fullstack: Backend (Ruby on rails, Elixir/Phoenix), Frontend (AngularJS), CRM integration (NodeJS); developed and deployed on AWS (EC2/S3/CloudFront/RDS/ElastiCache); best practice of micro-services, docker/k8s, many 3rdparty services (Twilio, Firebase, Loggly, LaunchDarkly, Datadog, NewRelic, Looker, .etc) are integrated.  Developing stat service & dashboards: data pipeline transmits realtime data from mySQL binlogs, via logstash, kafka to ElasticSearch, from where Elixir REST API fetch data and respond to customers concurrently and efficiently.  Refactoring core services from Ruby to Elixir, to reduce database load and memory cost and make the system more scalable.

 Independently designed and implemented a new RTS mobile game server using Erlang* Erlang, Python, C++; Linux; AWS-EC2* Flexible and replaceable coding structure and modular design: ** Networking: TCP/ self implemented reliable UDP ** Serializer/Compressor: protobuf(zlib)/json(msgpack) ** Security: RSA + AES-CBC ** Database: MongoDB ** CDN: AWS-S3/Cloudfront ** LoadBalancer: AWS-ELB ** Matchmaking: Trueskill* Deterministic lockstep as synchronization; AOI (Area of Interest) and flexible sampling rate method for reducing character movement related traffic packets; heartbeat and snapshot used for disconnection, reconnection and resync.* Supporting multiplayer realtime PvP (5vs5 and unlimited Free For All) and spectator mode allowing thousands of followers attached in one channel (an implemented spectator mode half a year earlier than PUBG's came out).* Flexible concurrent channels and multi-erlang-node cluster architecture supporting 40000+ concurrent players per EC2 instance efficiently. * Integrated with Unity C# client-side and solved plenty of desync, lag, low-frame-rate, high-traffic-cost and other performance issues using distributed-systems theories and practical debugging skills; thoughtful and experienced on synchronization, lag compensation, reduce/hide latency and more realtime networking related topics. Participated in developing Bigworld-like MMO server engine for mobile game products * Developed using C++ for engine core and Python for application layer using MySQL, XML/JSON and AWS. * Imported Nvidia PhysX for physics/collision simulation, and behavior tree as for AI. * Optimized AOI calculation, memory-leak, database sharding, network performance and stability.

Beaumont, Tx, Us

 Graduate Thesis: Whoo, an Android face recognition app (Java, OpenCV, ML, TCP/IP).  Car2Car distributed communication simulator (Linux, FtkGUI, distributed consensus algorithms).  Wireless Sensor Network and nesC programming on TinyOS: 802.11*, ZigBee, IoT and more protocols  CUDA parallel programming on NVIDIA GPUs: multi-core-CPU & GPU profiling and optimizations  Robot programming in SHARC assembly: robotics, assembly, sensors, .etc

CVTE Co., Ltd is China’s largest television board provider. (www.cvte.cn) Smart TV development: Java/Android, C++(NDK), C(kernel, drivers).  Developed a Sling-box-like product with streaming thousands of traditional TV channels, end-to-end.  Infra/DevOps: designed and refactored unified API, using which optimized development-cycle and built an automatic test system for quality control of mass-production. Developed software for GPS navigation, vehicle-electronics, smart-ad-panel and other devices.

Master Of Science (Ms), Computer Science

Bachelor Of Science (Bs), Computer Science