Mohanad Elsafty

Amazon Web Services (AWS) - Dublin, Ireland

• Building DynamoDB MemDS (In-Memory MetaData Storage)

  Java, Rust, C++, Python, UDP/TCP.

• Engineered core in-memory metadata service (Java) for DynamoDB, serving billions of requests/sec with ultra-low latency.
• Designed and implemented sharding architecture to distribute metadata across hosts, reducing memory footprint and improving scalability.
• Built shard discovery protocol (Rust) for clients, including heartbeat and failure-detection mechanisms; delivered full end-to-end implementation.
• Automated deployments and scaling across AWS regions; benchmarked new features and optimized low-level performance (ENI, RSS tables, IRQ).
• Handled on-call operations, resolving critical production incidents and troubleshooting infrastructure issues.

Singapore Telecommunications

• Building the data fabric solution of Singtel

  Apache Spark, Apache Hadoop, Apache Airflow, Amazon AWS, Microsot Azure, Python, Rust, Scala.

• Developed an encryption solution ensuring secure transfer of sensitive data to the cloud.
• Integrated with existing frameworks, including Apache Spark, by providing User-Defined Functions (UDFs) in Java for encrypting, decrypting, and HMAC operations on DataFrame columns.
• Developed a Kafka plugin to encrypt or HMAC messages during transmission, ensuring data security from source to sink. Decryption is performed at the receiving end, maintaining data integrity throughout the data pipeline.

  Java, Scala, Python, Google Tink

E-commerce company

• Enhanced Spark history server, resulting in 80% performance improvement with larger datasets.
• Developed logs aggregation for Yarn/HDFS logs, saving 3 hours weekly.
• Designed low-memory fingerprint for extended offline analysis of FSIMAGE.
• Engineered block-based InputFormat for DistCp, shortening data transfer time by 20%.
• Enhanced DFSClient and NameNode for read/write operations.
• Engineered petabyte-scale data Retention Service, saving 15% of storage.
• Architected universal s3gateway solution for multiple clusters access.
• Devised efficient fair call queue and Quality of Service mechanisms for s3gateway.

  Apache Spark, Apache Hadoop/HDFS, Apache Ozone, Apache Airflow, Apache Ratis, AWS, RocksDB, Kubernetes, Golang, Scala, Java, JavaScript, C++

E-commerce company

• Revamped ZMM system, reducing runtime by 41% and cost by 70.6%.
• Optimized SQL queries on Amazon Redshift, reducing ingestion time by 66%.
• Pioneered media attribution model based on Hidden Markov model.
• Collaborated on visualization of model outcomes using Apache Superset.
• Led development of automated price prediction system, optimizing training time.
• Devised data ingestion techniques and optimized cluster size.

  AWS(S3, EMR, ECS, EKS, CodeBuild), Apache Airflow, Python, PySpark, R, SQL, Pandas, NumPy, Notebooks

IT Services and IT Consulting

• Developed VOIP android application and dedicated webservice.
• Participated in mobile application development and optimized backend API response time.

  Python, Django, NodeJS, Angular, Ionic

IT Services and IT Consulting

• Constructed certification module with Arabic language support.
• Built filter and tagging module for optimized search on OpenEDX.
• Designed GoogleAppEngine-based web application and crafted python wrappers for G-Suite APIs.

  Google Cloud, GoogleAppEngine, Python, Django, ElasticSearch, OpenEDX