
Zach Puller contributed to the NVIDIA/spark-rapids repository over 13 months, building and optimizing GPU-accelerated data processing features for Spark. He engineered memory-aware shuffle coalescing, dynamic memory limit calculations, and GPU-based serialization paths, addressing performance and reliability in large-scale distributed systems. Using Scala, Python, and CUDA, Zach refactored profiling instrumentation, enhanced containerization with Docker, and improved CI/CD stability through targeted dependency upgrades and test automation. His work included debugging memory management for integrated GPUs, refining partitioning logic, and automating documentation for profiling ranges. These efforts resulted in more predictable resource usage, robust GPU workload handling, and streamlined deployment pipelines.
January 2026 performance summary for NVIDIA/spark-rapids: Delivered memory-aware GPU data processing enhancements with a retry-on-OOM split policy for shuffle coalescing and default-enabled GPU kudo reads, plus corrected cuDF partitioning API offset handling. Key changes include a memory-aware split policy with target-size and byte-size-based table sequence splitting, and configuration-driven enablement of GPU kudo reads with validation tests. Fixed cuDF partitioning offset handling to ensure correct partition counts. Impact: improved memory efficiency, stability, and throughput for GPU-accelerated Spark workloads; more predictable partitioning and easier feature adoption through configuration. Technologies/skills: GPU-accelerated Spark, cuDF integration, memory-aware algorithm design, test automation, and configuration-driven feature enablement.
January 2026 performance summary for NVIDIA/spark-rapids: Delivered memory-aware GPU data processing enhancements with a retry-on-OOM split policy for shuffle coalescing and default-enabled GPU kudo reads, plus corrected cuDF partitioning API offset handling. Key changes include a memory-aware split policy with target-size and byte-size-based table sequence splitting, and configuration-driven enablement of GPU kudo reads with validation tests. Fixed cuDF partitioning offset handling to ensure correct partition counts. Impact: improved memory efficiency, stability, and throughput for GPU-accelerated Spark workloads; more predictable partitioning and easier feature adoption through configuration. Technologies/skills: GPU-accelerated Spark, cuDF integration, memory-aware algorithm design, test automation, and configuration-driven feature enablement.
December 2025 monthly summary for NVIDIA/spark-rapids focused on delivering GPU-backed performance improvements and robustness in shuffle workloads. Key feature delivered: GPU Shuffle Exchange Retry and Partitioning Enhancement, designed to handle memory constraints by splitting batches and adding a retry mechanism within the GPU execution context. This work also involved refining partitioning logic to improve stability and throughput of data processing tasks on GPUs.
December 2025 monthly summary for NVIDIA/spark-rapids focused on delivering GPU-backed performance improvements and robustness in shuffle workloads. Key feature delivered: GPU Shuffle Exchange Retry and Partitioning Enhancement, designed to handle memory constraints by splitting batches and adding a retry mechanism within the GPU execution context. This work also involved refining partitioning logic to improve stability and throughput of data processing tasks on GPUs.
Month: 2025-11 – NVIDIA/spark-rapids work focused on GPU-accelerated data processing and deployment reliability. Delivered GPU acceleration and configurability enhancements for Kudo, including optional GPU deserialization to speed up shuffle reads and a dynamic override to configure Kudo GPU slicing during test runs, enabling faster test cycles and more flexible performance tuning. Added GPU shuffle reads support in the Kudo plugin to boost throughput for GPU-enabled workloads. Completed environment compatibility and maintenance updates, upgrading the core GPU/UCX stack: UCX to 1.19.1-rc2, CUDA 13, and Rocky Linux-based Dockerfiles, with improved docs and tests for the new configurations.
Month: 2025-11 – NVIDIA/spark-rapids work focused on GPU-accelerated data processing and deployment reliability. Delivered GPU acceleration and configurability enhancements for Kudo, including optional GPU deserialization to speed up shuffle reads and a dynamic override to configure Kudo GPU slicing during test runs, enabling faster test cycles and more flexible performance tuning. Added GPU shuffle reads support in the Kudo plugin to boost throughput for GPU-enabled workloads. Completed environment compatibility and maintenance updates, upgrading the core GPU/UCX stack: UCX to 1.19.1-rc2, CUDA 13, and Rocky Linux-based Dockerfiles, with improved docs and tests for the new configurations.
October 2025: Delivered platform uplift for UCX/CUDA in container images across Rocky Linux and Ubuntu, enabling UCX 1.19.1-rc1 and CUDA 13.0.1 in example Dockerfiles and Jenkins environments. Added Rocky Linux support for CUDA11 UCX builds when CUDA13 UCX builds are unavailable, and ensured both RDMA and non-RDMA configurations are covered. Standardized performance instrumentation by migrating NVTX-based timing to NvtxId/NvtxIdWithMetrics across CollectTimeIterator, broadcast hash join profiling, and related docs. Changed default Spark RAPIDS memory behavior by disabling offHeapLimit by default for improved stability. All changes are ready for broader deployment, improved performance visibility, and more predictable memory usage in production.
October 2025: Delivered platform uplift for UCX/CUDA in container images across Rocky Linux and Ubuntu, enabling UCX 1.19.1-rc1 and CUDA 13.0.1 in example Dockerfiles and Jenkins environments. Added Rocky Linux support for CUDA11 UCX builds when CUDA13 UCX builds are unavailable, and ensured both RDMA and non-RDMA configurations are covered. Standardized performance instrumentation by migrating NVTX-based timing to NvtxId/NvtxIdWithMetrics across CollectTimeIterator, broadcast hash join profiling, and related docs. Changed default Spark RAPIDS memory behavior by disabling offHeapLimit by default for improved stability. All changes are ready for broader deployment, improved performance visibility, and more predictable memory usage in production.
September 2025 performance summary for NVIDIA/spark-rapids: Implemented GPU memory management enhancements for integrated GPUs to improve stability and debugging. Delivered configurable GPU/host memory split, added new config options and testing utilities, and introduced instrumentation to detect duplicate updateMaxMemory calls for easier debugging. This work reduces memory-related failures on integrated GPUs and improves overall reliability for memory-sensitive workloads.
September 2025 performance summary for NVIDIA/spark-rapids: Implemented GPU memory management enhancements for integrated GPUs to improve stability and debugging. Delivered configurable GPU/host memory split, added new config options and testing utilities, and introduced instrumentation to detect duplicate updateMaxMemory calls for easier debugging. This work reduces memory-related failures on integrated GPUs and improves overall reliability for memory-sensitive workloads.
August 2025 monthly summary for NVIDIA/spark-rapids focusing on stability, memory management, and profiling instrumentation. Delivered key enhancements to reduce memory footprint, improve memory usage control, and expand performance visibility for tuning and AQE compatibility.
August 2025 monthly summary for NVIDIA/spark-rapids focusing on stability, memory management, and profiling instrumentation. Delivered key enhancements to reduce memory footprint, improve memory usage control, and expand performance visibility for tuning and AQE compatibility.
July 2025 monthly summary for NVIDIA/spark-rapids focused on delivering robust memory management for GPU-accelerated workloads and accelerating data shuffles via GPU serialization.
July 2025 monthly summary for NVIDIA/spark-rapids focused on delivering robust memory management for GPU-accelerated workloads and accelerating data shuffles via GPU serialization.
June 2025 monthly summary for NVIDIA/spark-rapids focusing on reliability and resource predictability in the GPU memory subsystem. Delivered two primary items: (1) dynamic CPU memory limit calculation in GpuDeviceManager with explicit config precedence, Spark executor memory overhead, and host memory as fallback (4GB minimum), and (2) a shell-shebang fix for prioritize-commits.sh to ensure correct execution and prevent downstream syntax errors. Strengthened observability by aligning logs with the derivation of memory limits.
June 2025 monthly summary for NVIDIA/spark-rapids focusing on reliability and resource predictability in the GPU memory subsystem. Delivered two primary items: (1) dynamic CPU memory limit calculation in GpuDeviceManager with explicit config precedence, Spark executor memory overhead, and host memory as fallback (4GB minimum), and (2) a shell-shebang fix for prioritize-commits.sh to ensure correct execution and prevent downstream syntax errors. Strengthened observability by aligning logs with the derivation of memory limits.
Month: 2025-05 | Key features delivered: Nvtx profiling instrumentation enhancements for RapidsShuffleInternalManagerBase in NVIDIA/spark-rapids, including migration of NVTX ranges to NvtxRangeWithDoc and introduction of NvtxId constants for shuffle operations, with code updated to use the new constants. Result: clearer profiling documentation and improved maintainability of the shuffle manager.
Month: 2025-05 | Key features delivered: Nvtx profiling instrumentation enhancements for RapidsShuffleInternalManagerBase in NVIDIA/spark-rapids, including migration of NVTX ranges to NvtxRangeWithDoc and introduction of NvtxId constants for shuffle operations, with code updated to use the new constants. Result: clearer profiling documentation and improved maintainability of the shuffle manager.
April 2025 monthly summary for NVIDIA/spark-rapids. Key features delivered involve NVTX profiling enhancements and documentation: introduced NvtxRangeWithDoc to associate documentation strings with NVTX profiling ranges, migrated existing NVTX range usage to the new class for clearer profiling, and auto-generated a README listing documented ranges. This work is accompanied by commits 41cdcdb000db11018c77331b0b1df5bfc27d9d5c and edcd79707158a297deba22e2e26da76adfc9fc74, delivering improved profiling clarity, observability, and maintainability. Major bug fix: Parquet LZ4 Test Suite Reliability, reverting xfailed tests after the underlying Hadoop LZ4 format issue in cudf was resolved (commit d565f88cffe53a605057f87dd536f58a7e31ebfd). Overall impact and accomplishments: stronger profiling instrumentation and test reliability, leading to faster CI feedback and reduced debugging time. Technologies/skills demonstrated: NVTX instrumentation and C++/CUDA profiling patterns, code refactor and documentation automation, test hygiene and CI reliability, cross-team collaboration.
April 2025 monthly summary for NVIDIA/spark-rapids. Key features delivered involve NVTX profiling enhancements and documentation: introduced NvtxRangeWithDoc to associate documentation strings with NVTX profiling ranges, migrated existing NVTX range usage to the new class for clearer profiling, and auto-generated a README listing documented ranges. This work is accompanied by commits 41cdcdb000db11018c77331b0b1df5bfc27d9d5c and edcd79707158a297deba22e2e26da76adfc9fc74, delivering improved profiling clarity, observability, and maintainability. Major bug fix: Parquet LZ4 Test Suite Reliability, reverting xfailed tests after the underlying Hadoop LZ4 format issue in cudf was resolved (commit d565f88cffe53a605057f87dd536f58a7e31ebfd). Overall impact and accomplishments: stronger profiling instrumentation and test reliability, leading to faster CI feedback and reduced debugging time. Technologies/skills demonstrated: NVTX instrumentation and C++/CUDA profiling patterns, code refactor and documentation automation, test hygiene and CI reliability, cross-team collaboration.
February 2025 monthly performance for NVIDIA/spark-rapids focused on delivering a robust performance baseline and stable CI while preparing for broader hardware support. Key work centered on UCX 1.18 upgrade across Dockerfiles with a CUDA default of 12.8.0 to enable improved performance, broader hardware compatibility, and alignment with newer UCX features. A deliberate stabilization step followed to maintain CI reliability when the UCX upgrade introduced test instability.
February 2025 monthly performance for NVIDIA/spark-rapids focused on delivering a robust performance baseline and stable CI while preparing for broader hardware support. Key work centered on UCX 1.18 upgrade across Dockerfiles with a CUDA default of 12.8.0 to enable improved performance, broader hardware compatibility, and alignment with newer UCX features. A deliberate stabilization step followed to maintain CI reliability when the UCX upgrade introduced test instability.
January 2025 monthly summary for NVIDIA/spark-rapids: Focused on performance and reliability improvements to the Spill Framework. Key changes include bounce buffer pools for pool-based buffer management with configurable sizes and counts, enabling concurrent spill and read paths; refactoring SpillFramework IO to run outside locked sections; and adding state variables to manage spilling and closing concurrently for non-blocking, consistent spill state. These deliver higher throughput, reduced contention in multi-threaded spill workloads, and more reliable end-to-end data processing in GPU-accelerated pipelines.
January 2025 monthly summary for NVIDIA/spark-rapids: Focused on performance and reliability improvements to the Spill Framework. Key changes include bounce buffer pools for pool-based buffer management with configurable sizes and counts, enabling concurrent spill and read paths; refactoring SpillFramework IO to run outside locked sections; and adding state variables to manage spilling and closing concurrently for non-blocking, consistent spill state. These deliver higher throughput, reduced contention in multi-threaded spill workloads, and more reliable end-to-end data processing in GPU-accelerated pipelines.
Month 2024-11 focused on increasing GPU throughput and improving observability in NVIDIA/spark-rapids. Implemented two major features with code changes and documentation updates, enabling larger batch sizes and providing visibility into host memory usage during Spark tasks. These changes unlock higher throughput, better resource utilization, and improved operability for performance tuning.
Month 2024-11 focused on increasing GPU throughput and improving observability in NVIDIA/spark-rapids. Implemented two major features with code changes and documentation updates, enabling larger batch sizes and providing visibility into host memory usage during Spark tasks. These changes unlock higher throughput, better resource utilization, and improved operability for performance tuning.

Overview of all repositories you've contributed to across your timeline