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Kousuke Saruta

PROFILE

Kousuke Saruta

Over 11 months, contributed to the apache/spark repository by engineering features and fixes that advanced reliability, security, and performance across Spark’s core and UI layers. Delivered enhancements such as Java 22+ compatibility, multi-directory support in the Spark History Server, and new Scala and Python bindings for vector functions. Addressed concurrency and CI stability through targeted bug fixes and dynamic artifact generation, while modernizing the Web UI with Bootstrap and improving security via job description redaction and constant-time authentication. Leveraged Scala, Java, and Python to implement robust build automation, test infrastructure, and backend improvements, supporting maintainable, enterprise-ready Spark deployments.

Overall Statistics

Feature vs Bugs

48%Features

Repository Contributions

95Total
Bugs
32
Commits
95
Features
30
Lines of code
10,699
Activity Months11

Your Network

412 people

Same Organization

@amazon.co.jp
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Work History

June 2026

9 Commits • 3 Features

Jun 1, 2026

June 2026 highlights for apache/spark: Key features delivered include Scala/Python bindings for vector functions; a dedicated sort-merge operator for AS-OF joins with spill-to-disk support; and Spark SQL job description redaction aligned with spark.sql.redaction.string.regex. Major fixes: CI reliability for pyspark-connect-old-client by correcting fork PR clone source, and test stability improvements (sql_keywords doctest replacement and live-table handling in AutoCdcScd1FullRefreshSuite). Overall impact: reduced CI churn, expanded analytics capabilities, stronger UI security, and improved query performance. Technologies demonstrated: Scala/Python bindings, Spark SQL, sort-merge join engineering, spill-to-disk, UI redaction, and test/CI instrumentation.

May 2026

7 Commits • 2 Features

May 1, 2026

May 2026 (apache/spark) delivered reliability, security, and private-repo readiness improvements across build, CI, and runtime integration. Key outcomes include a robust local publish workflow, private-repo support for Hive metastore jars, Docker/Python build compatibility, static-type checking stability with PyArrow 24, and security hardening for authentication. Overall impact: - Smoother developer experience with local publish (Sbt publishLocal) and controllable source JAR publication. - Private repository support enabled for Hive metastore dependencies, expanding enterprise deployment options. - Build and image creation reliability improved (Docker get-pip.py URL for Python 3.9). - CI lint stability maintained in the face of PyArrow 24 changes. - Strengthened authentication security against timing attacks. Technologies/skills demonstrated: - SBT, Maven publish workflow adjustments; env var driven feature toggles (PUBLISH_PACKAGE_SRC). - Ivy settings integration for private repos; environment-driven test infrastructure (SPARK_VERSIONS_SUITE_IVY_SETTINGS variants). - Dockerfile maintenance for multi-Python-version images; Python packaging workflows. - Python typing considerations with PyArrow 24; mypy configuration tweaks to skip dynamic PyArrow stipulations. - Security engineering: constant-time comparison for authentication secrets.

April 2026

12 Commits • 8 Features

Apr 1, 2026

April 2026 monthly summary for Apache Spark engineering. Focused on stabilizing the release process, eliminating binary artifacts through dynamic test artifact generation, and improving UI performance and CI reliability. The team delivered concrete features and fixes that reduce maintenance burden, speed up CI cycles, and improve product quality and test reproducibility.

March 2026

15 Commits • 8 Features

Mar 1, 2026

Monthly summary for 2026-03 (apache/spark). Focused on delivering business value through Java compatibility, improved observability, UI modernization, and stronger test coverage. Key achievements span feature delivery, bug fixes, and infrastructure cleanups with measurable impact on runtime compatibility, operational efficiency, and developer productivity. Key features delivered and related impact: - ClosureCleaner Java 22+ compatibility: Reworked ClosureCleaner to work with Java 22+ by cloning indy lambdas via LambdaMetaFactory, enabling Spark workloads on newer JDKs without user-facing changes. This removes upgrade barriers for customers adopting Java 22+. - History Server (SHS) multi-log-dirs: Added support for multiple log directories via a comma-separated spark.history.fs.logDirectory, with per-directory display names (Log Source) in the UI and per-directory behavior; improves ops for multi-cluster or cross-tenant workflows and reduces manual log management. - SHS on-demand loading improvements: Populate accurate metadata immediately on-demand (instead of placeholders) by using mergeApplicationListing; added ability to disable log directory scanning by path pattern (spark.history.fs.update.scanDisabledPathPatterns) to reduce unnecessary scans and save costs on object stores. - Tests and QA enhancements for SHS: Expanded test coverage for multi-directory scenarios (removal, non-existent startup directories, recovery after inaccessibility, all directories unavailable, empty path entries, and name/count fallbacks) and added infra/test support for sql-api. - Web UI modernization and dependency cleanup: Removed legacy UI dependencies (jquery.mustache.js, jquery.blockUI.min.js, jquery.cookies) and updated UI to Bootstrap-based loading overlay; refactored related JS and tests, reducing JS footprint and aligning with modern UI standards. - Spark Connect interrupt handling fix: Resolved interrupt semantics for pending operations (moved postStarted into execution path, allowed Pending→Canceled/Failed transitions) and re-enabled SparkSessionE2ESuite interrupt tag tests; improves reliability of long-running or canceled remote executions. - Infra and build hygiene: Added .kiro to .gitignore to avoid leaking local config, and removed unused add-scala-test-sources from connect-common pom.xml; downstream build and repo hygiene improved. - Additional testing infrastructure: Introduced sbt_test_goals for sql-api in sparktestsupport to ensure sql-api tests run in GA. Overall impact and accomplishments: - Increased Java 22+ compatibility for Spark deployments, enabling customers to modernize their stacks with minimal risk. - Reduced log-scanning costs and improved log visibility across multiple log sources via SHS enhancements. - Improved on-demand listings with accurate metadata, delivering faster, more trustworthy UI information. - Modernized Web UI with reduced dependencies and improved loading UX, simplifying maintenance and improving performance. - Strengthened reliability of Spark Connect interruption behavior and expanded test coverage across critical paths. - Cleaner repo and testing infra, enabling faster iteration and GA readiness. Technologies and skills demonstrated: - Java 22+ compatibility work (ClosureCleaner, final-field handling in hidden lambdas), LambdaMetaFactory usage. - Spark History Server architecture (logDirectory, SHS UI, on-demand loading, scan patterns). - sbt/Scala, testing/GA pipelines, and CLI tooling. - Web UI modernization (Bootstrap-based overlay, ESLint ignore patterns), and JS/UI refactoring. - Build tooling and repo hygiene improvements (pom.xml cleanups, .gitignore hygiene).

February 2026

5 Commits • 2 Features

Feb 1, 2026

February 2026 monthly summary for Apache Spark: Achieved key build reliability improvements, upgraded testing infrastructure, and fixed critical Web UI CSP issues, delivering stronger performance, test coverage, and user experience with minimal user-facing changes.

January 2026

20 Commits • 2 Features

Jan 1, 2026

January 2026 monthly summary for apache/spark focusing on delivering business value through stability, security, and deployment improvements, plus concurrency and test reliability enhancements. Delivered foundational platform upgrades, hardened build tooling, and expanded deployment options, enabling more reliable releases and broader Hadoop deployments.

December 2025

8 Commits • 2 Features

Dec 1, 2025

December 2025 monthly summary for apache/spark focusing on business value, security, stability, and compatibility improvements. Key features delivered include UI hardening for history rendering and Hive 4.1 compatibility for Hive metastore support. Major bugs fixed address safety and memory issues and security vulnerabilities, complemented by dependency and CI improvements to enhance reliability and maintainability.

November 2025

5 Commits • 1 Features

Nov 1, 2025

November 2025: Focused on platform upgrade readiness, CI reliability, and dependency maintenance for apache/spark. Delivered a Servlet compatibility fix to support Servlet 6.0 and Jetty 12 upgrade, stabilized CI with test imports cleanup and Oracle image upgrades, improved cross-component utility reuse by relocating Java version checks, and modernized dependencies (commons-codec 1.20.0). These efforts reduced upgrade risk, shortened feedback loops, and preserved test coverage across core components.

October 2025

9 Commits • 1 Features

Oct 1, 2025

Month 2025-10: Delivered high-impact features and stability improvements across Spark Connect, build tooling, and test reliability, creating measurable business value through configurability, robustness, and maintainability.

September 2025

4 Commits • 1 Features

Sep 1, 2025

September 2025 (apache/spark) monthly summary focusing on test stability improvements and test coverage enhancements across Spark core test suites. Key outcomes include stabilizing SparkConnectServiceSuite and SparkSessionE2ESuite tests, addressing flaky behavior during status transitions and concurrency, and re-enabling AmmoniteTest tests in Maven builds to improve coverage. The work improves CI reliability, reduces flaky test noise, and accelerates feedback for feature development.

July 2025

1 Commits

Jul 1, 2025

This month focused on reliability improvements for streaming test flows in Apache Spark, with a critical fix to interrupt handling in the SparkSessionE2ESuite that resolved a hanging scenario and prevents indefinite waits during streaming query interruptions.

Activity

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Quality Metrics

Correctness99.0%
Maintainability90.0%
Architecture92.6%
Performance90.8%
AI Usage41.2%

Skills & Technologies

Programming Languages

BashCSSDockerfileHTMLJSONJavaJavaScriptNonePythonScala

Technical Skills

API developmentApache SparkBig DataBootstrapBuild AutomationBuild ConfigurationCI/CDCSSCode QualityCode RefactoringContainerizationContinuous IntegrationData ProcessingDataFrame ManipulationDevOps

Repositories Contributed To

1 repo

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

apache/spark

Jul 2025 – Jun 2026
11 Months active

Languages Used

ScalaBashYAMLPythonShellXMLJavaJSON

Technical Skills

Scalabackend developmenttestingContinuous IntegrationDevOpsTesting