# Eren Avşaroğulları

> Principal Software Engineer at Workday

Location: San Francisco Bay Area, United States
Profile: https://flows.cv/erenavaroullar

Eren is highly motivated software engineer and enthusiast on database internals and optimizations, high throughput systems design, distributed systems challenges.

His current areas of interest are:
- Rust, Scala, Java
- Columnar & Vectorized Query Engines Internals and Optimization Techniques, 
- Adaptive Query Execution Internals (Dynamic Join Selection, Skew Mitigation, Coalescing Shuffle Partitions), 
- OLTP, OLAP, Streaming, Vector Database Systems, 
- Join Optimizations (BroadcastHashJoin, ShuffleHashJoin, SortMergeJoin, BloomFilterJoin), 
- Skew Mitigation Improvements for SortMergeJoin and ShuffleHashJoin,
- Memory Consumers Optimizations (ExternalSorter, Spark: BytesToBytesMap) and Disk Spilling Support,
- Batch and Stream Processing Engines (Apache Spark, Apache Flink),
- Open Table Formats (Apache Iceberg and Delta-IO) Integrations,
- Distributed & Parallel Computing, 
- High Availability & Scalability.

He is OSS contributor (Apache Spark, Apache DataFusion, Apache Pulsar, Apache Heron and Spring Integration), conference speaker and member of Apache Software Foundation(ASF).

He hold a B.Sc. degree in Electrical & Electronics Engineering and a M.Sc. degree in Control & Automation Engineering.

Technical Articles: 
https://medium.com/@erenavsarogullari
https://dzone.com/users/938353/eren_avsarogullari.html

Github: 
https://github.com/erenavsarogullari

Goodreads:
https://www.goodreads.com/erenavsarogullari

## Work Experience
### Principal Software Engineer @ Workday Data Analytics (Apache Spark Platform Team) @ Workday
Jan 2022 – Present | San Francisco, California, United States
- Member of Apache Spark Platform Team,
- Experience on Spark Query Compilation and Execution,
- Extending Spark Adaptive Query Execution(AQE),
- Improving Spark AQE Skew Mitigation Support for SortMergeJoin and ShuffleHashJoin,
- Extending Spark Memory Management/Consumers and Physical Operators Disk Spilling Support,
- Fixing Spark Driver and Executor Side Memory Problems,
- Tuning Spark Shuffle Partitioning,
- Extending ShuffleHashJoin & BloomFilterJoin features and get production ready for critical and complex queries,
- Working on Spark Scalability, Resilience and Performance,
- Lead Engineer of Progressive Spark Upgrades (Spark is backbone of Prism Data Analytics Platform),
- Lead Engineer of Architectural Improvements of Spark Observability Platform
- Experience on Rust, Scala, Java, Akka, Functional Programming, Distributed Query Execution, Big Data Technologies(e.g: Apache Spark, Hadoop YARN, HDFS, Kafka, S3, AWS, Kubernetes),
- Working on Apache Spark In-house and OSS Patches, ETL Batch Data Processing Pipelines, Distributed Computing Challenges, Performance Improvements.

### Senior Data Engineer @ Workday Prism Analytics (Apache Spark Platform Team) @ Workday
Jan 2019 – Jan 2022 | San Francisco, California, United States
- Member of Apache Spark Runtime Team
- Lead Engineer of Progressive Spark Upgrades (Spark is backbone of Prism Data Analytics Platform)
- Professional Experience on Scala, Akka, Functional Programming, Distributed Query Execution, Big Data Technologies(e.g: Apache Spark, Hadoop YARN, HDFS, Kafka)
- Working on Apache Spark OSS Patches, ETL Batch Data Pipelines, Distributed Computing Challenges, Performance Improvements.
- Experience on AWS, S3, Docker, Kubernetes.

### Senior Data Engineer @ Workday
Jan 2015 – Jan 2019 | Dublin, Ireland
- Member of Data Transformation Team
- Professional Experience on Scala, Akka, Spray, Big Data Technologies(e.g: Apache Spark, YARN, HDFS, Kafka)
- Working on ETL Batch Pipelines
- Experience on AWS, S3, Docker, Kubernetes
- Working on Data Pipelines, Distributed Computing Challenges, Performance.

### Apache { Spark, DataFusion, Pulsar and Heron } Contributor @ The Apache Software Foundation
Jan 2016 – Present | San Francisco Bay Area
Apache Spark: 
- Contributed to Spark Job Scheduler Module

Merged Pull Requests: 
https://github.com/apache/spark/pulls?utf8=%E2%9C%93&q=author%3Aerenavsarogullari

Apache DataFusion:
- Contributed to DataFusion functions and functions-array crates.

Merged Pull Requests: 
https://github.com/apache/datafusion/pulls?q=is%3Apr+author%3Aerenavsarogullari

Apache Pulsar:
- Pulsar-Flink Connector Batch API Support to write Flink DataSets in text, csv and json formats to user-defined Pulsar topics
- Pulsar-Netty I/O Connector: This connector listens incoming TCP messages by initializing TCP server and writes user-defined Pulsar topic.
- Contributed projects' other modules such as Auth, Message Routing, Client API by refactoring.
- Contributed project by reviewing some of the patches.

Merged Pull Requests:
https://github.com/apache/pulsar/pulls?q=is%3Apr+author%3Aerenavsarogullari

Apache Heron:
- Developed Scala Streamlet API by supporting different transformation operations.
- Contributed to Java Streamlet API by applying patches and reviewing some of the patches.

Merged Pull Requests:
https://github.com/apache/incubator-heron/pulls?q=is%3Apr+author%3Aerenavsarogullari+is%3Aclosed

### Senior Software Engineer @ Brite:Bill
Jan 2014 – Jan 2015 | Dublin, Ireland
- Leading Product Development Team
- Architecture, Design, Implementation and Testing of Enterprise Java Software Systems,
- Functional & Non Functional Requirement(NFR) Analysis and Implementations,
- Profiling Java Systems and Working on Performance Improvement Tasks,
- Subject Matter Expert(SME) – Spring Integration & RabbitMQ,
- Agile Software Development Skills(Scrum),
- Developing new releases, CRs and Bug­ fixing,
- Developing and Analysing Unit, Integration and Load Tests,
- Operational Support(Critical Issue Solving, HotFix)
- Giving technical trainings

### Senior Software Design & Development Engineer @ Sentenial
Jan 2012 – Jan 2014 | Dublin, Ireland
- Architecture, Design, Implementation and Testing of Enterprise Java Software and
Middlewares
- Non Functional Requrement(NFR) Analysis and Implementations
- Working on Performance Improvement Tasks
- Subject Matter Expert(SME) - Distributed Cache Technologies & Live Clustering
- Agile Software Development Skills
- Developing new releases, CRs and Bug-fixing.
- Developing and Running Unit, Integration and Load Tests 
- Operational Support(Critical Issue Solving, HotFix)
- Test Support
- Writing Technical Design Document

### Senior Software Design & Development Engineer @ Turkcell Technology Research and Development
Jan 2010 – Jan 2012
- Project Development Leadership
- Turkcell Value-Added-Service(VAS) Platforms’ Ownership
- Architecture, Design, Implementation and Testing of Enterprise Java Software and 
Middlewares
- Agile Software Development Skills
- Mentoring & Coaching of Junior/Intermediate Developers
- Developing new features(New Phases, CRs, Enhancements and Bug-fix).
- Developing and Running Unit, Integration and Load Tests by using Test Frameworks, 
Simulator Applications and External Tools.
- Analysis Support for the new features and roadmap of the product
- Operational Support(Hardware Requirement, Deployment, HotFix)
- Test Support
- Giving Technical Trainings
- Writing Technical Design Document(TDD), Operational Deployment 
Document(ODD) and User Manual(UM) for the new applications

### Software Design & Development Specialist @ Nortel Networks
Jan 2007 – Jan 2010
- SIP-PBX OAM (System Management and Povisioning) Side Ownership
- Analysis Support for the new features
- Taking design and development responsibilities
- Developing Presentation(UI), Service(Core/Business), Data Access Layer
- Developing new features(New Phases, CRs, Enhancements and Bug-fix).
- Running Unit and Integration Tests
- Doing Code Reviews
- Product Verification Support
- Writing Technical Design/Development Documentation


## Education
### Master's degree in Control & Automation Engineering Department
Istanbul Technical University

### Bachelor's degree in Electrical & Electronic Engineering Department
Karadeniz Technical University


## Contact & Social
- LinkedIn: https://linkedin.com/in/erenavsarogullari
- GitHub: https://github.com/erenavsarogullari

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Source: https://flows.cv/erenavaroullar
JSON Resume: https://flows.cv/erenavaroullar/resume.json
Last updated: 2026-04-12