
Xianming Lei contributed to the apache/celeborn and apache/spark repositories, focusing on backend reliability, performance, and observability. Over four months, he enhanced cost tracking and storage distribution in distributed systems, improved fault tolerance in shuffle readers, and clarified configuration and quota messaging. His work included optimizing the OrcSerializer in Apache Spark by reusing TypeDescription objects, which reduced serialization overhead for large datasets. Using Scala and Java, Xianming addressed concurrency, error handling, and system metrics, delivering targeted fixes and optimizations. His contributions demonstrated a strong grasp of distributed backend architecture, with changes validated through unit tests and targeted benchmarks.
December 2025: Delivered a performance-focused enhancement for OrcSerializer in Apache Spark that reuses TypeDescription during serialization to avoid repeated schema parsing for maps, arrays, and structs, delivering substantial speedups on large datasets. The change, implemented in commit 00163b828b33406e0500c6dec0e5989b7b248c86 and associated with SPARK-54754, was validated with existing unit tests and targeted benchmarks. No user-facing behavior changes. This work improves throughput for Spark SQL ORC workloads and demonstrates effective bottleneck identification and optimization.
December 2025: Delivered a performance-focused enhancement for OrcSerializer in Apache Spark that reuses TypeDescription during serialization to avoid repeated schema parsing for maps, arrays, and structs, delivering substantial speedups on large datasets. The change, implemented in commit 00163b828b33406e0500c6dec0e5989b7b248c86 and associated with SPARK-54754, was validated with existing unit tests and targeted benchmarks. No user-facing behavior changes. This work improves throughput for Spark SQL ORC workloads and demonstrates effective bottleneck identification and optimization.
In Oct 2025, delivered a fault-tolerance enhancement for CelebornShuffleReader in the apache/celeborn repo to improve reliability in dual-replica configurations by selecting replica partition locations based on taskAttemptId during reader creation. This change mitigates single-point failures when primary data is corrupted and a retry occurs, reducing job failures in distributed shuffle workloads. No user-facing behavior changes; existing unit tests validate the fix. The work ties to CELEBORN-2032 and closes related issue #3490.
In Oct 2025, delivered a fault-tolerance enhancement for CelebornShuffleReader in the apache/celeborn repo to improve reliability in dual-replica configurations by selecting replica partition locations based on taskAttemptId during reader creation. This change mitigates single-point failures when primary data is corrupted and a retry occurs, reducing job failures in distributed shuffle workloads. No user-facing behavior changes; existing unit tests validate the fix. The work ties to CELEBORN-2032 and closes related issue #3490.
June 2025: Delivered targeted feature clarity, reliability, and messaging improvements for the Celeborn project (apache/celeborn). Focused on three areas with direct business value: 1) configuration clarity for stage reruns, 2) accurate throughput metrics during error scenarios, and 3) clearer quota-related messages to reduce operator risk and confusion. All changes preserve existing behavior while improving observability and maintainability. Key commits referenced for traceability wereede obfuscated in this view to CELEBORN-1719, CELEBORN-2033, and CELEBORN-1577.
June 2025: Delivered targeted feature clarity, reliability, and messaging improvements for the Celeborn project (apache/celeborn). Focused on three areas with direct business value: 1) configuration clarity for stage reruns, 2) accurate throughput metrics during error scenarios, and 3) clearer quota-related messages to reduce operator risk and confusion. All changes preserve existing behavior while improving observability and maintainability. Key commits referenced for traceability wereede obfuscated in this view to CELEBORN-1719, CELEBORN-2033, and CELEBORN-1577.
May 2025 monthly summary for apache/celeborn focused on reliability and performance improvements in cost accounting and storage distribution. Implemented two critical bug fixes with no user-facing changes, reinforced cost transparency, and improved resource utilization across the cluster. The work enhances billing accuracy, forecasting, and storage balance under concurrent workloads.
May 2025 monthly summary for apache/celeborn focused on reliability and performance improvements in cost accounting and storage distribution. Implemented two critical bug fixes with no user-facing changes, reinforced cost transparency, and improved resource utilization across the cluster. The work enhances billing accuracy, forecasting, and storage balance under concurrent workloads.

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