Stephen O'donnell
Senior Staff Engineer at Cloudera
Belfast, Northern Ireland, United Kingdom
Summary
🤩
Rockstar🎓
Top SchoolStephen O'donnell is a Senior Staff Engineer with nearly two decades of experience building high-performance data systems, currently focused on HDFS and Apache Ozone at Cloudera where he is a committer and PMC member. He brings deep Oracle expertise (13 years) and a pragmatic shift to Hadoop and NoSQL, having architected an enterprise data hub and evaluated Redis and Solr for low-latency workloads. His contributions to core open-source projects like Apache Hadoop and Ozone show a knack for backend robustness—optimising image loading, replication, and container lifecycle logic in large distributed storage systems. Comfortable across Java, Ruby, Rails and Linux administration, he blends development DBA skills with systems-level troubleshooting from customer-facing outage resolution to performance tuning. Based in Belfast, he combines rigorous academic training (MEng First Class) with a habit of personal projects, including Ruby apps and simple iOS utilities, reflecting continual curiosity beyond his day job.
12 years of coding experience
19 years of employment as a software developer
Master's Degree, Electrical and Electronics Engineering, First Class Honours, Master's Degree, Electrical and Electronics Engineering, First Class Honours at Queen's University Belfast
Github Skills (15)
container-management10
javas10
filesystem10
hdfs10
file-management10
hadoop10
replication10
performance-optimization10
back-end-development10
java10
distributed-systems9
distributed-file-system9
data-storage9
multithreading8
testing7
Programming languages (5)
Github contributions (5)
apache/ozone
Oct 2019 - Jan 2023
Scalable, reliable, distributed storage system optimized for data analytics and object store workloads.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1216 reviews, 170 commits, 550 PRs in 3 years 3 months
Contributions summary:Stephen primarily worked on back-end aspects of the Apache Ozone project, focusing on the SCM and related components. Contributions included fixing bugs in the QueryNode, enhancing node operational state management, and implementing improvements to container deletion processes. The user also made changes to various classes within the project, including DatanodeStateMachine, ContainerReplicaCount, and ReplicationManager.
scalableredundantapachebig-dataspark
apache/hadoop
Aug 2019 - Jun 2022
Apache Hadoop
Role in this project:Backend Developer
Backend DeveloperContributions:60 reviews, 29 commits, 52 PRs in 2 years 9 months
Contributions summary:Stephen primarily contributed to the Apache Hadoop project by implementing and improving core backend functionalities related to the Hadoop Distributed File System (HDFS). This includes optimizing the performance of image loading, addressing checksum issues in block metadata, and reducing memory usage during data node layout upgrades. The user also focused on improving the robustness of the system by handling exceptions in critical components, such as lease recovery during file closing and by refining the replication process.
apachebig-datasparkhadoopjava
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