apache/spark
Jul 2025 – Mar 2026
8 Months active
Languages Used
ScalaBashYAMLPythonShellXMLJavaJSON
Technical Skills
Scalabackend developmenttestingContinuous IntegrationDevOpsTesting
Kousuke Saruta
PROFILE
Kousuke Saruta
Sarutak contributed to the apache/spark repository by engineering robust backend and infrastructure improvements focused on reliability, security, and maintainability. Over eight months, Sarutak enhanced Spark’s test stability, modernized build systems, and delivered features such as multi-directory log support for the Spark History Server. Using Scala, Java, and JavaScript, Sarutak addressed concurrency issues in core components, implemented security hardening for the Web UI, and upgraded dependencies for compatibility with evolving platforms like Java 22+. The work demonstrated deep understanding of distributed systems and CI/CD pipelines, resulting in more resilient deployments and streamlined development workflows across Spark’s complex codebase.
Overall Statistics
Feature vs Bugs
62%Features
Repository Contributions
56Total
Bugs
8
Commits
56
Features
13
Lines of code
4,908
Activity Months8
Your Network
334 peopleSame Organization
@amazon.co.jp10
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Kouki KishidaMember
Taito KikuchiMember
Daisuke MiyamotoMember
Masashi TomookaMember
skisimoMember
Takamitsu IwaiMember
TomokiMember
Work History
March 2026
14 Commits • 4 Features
Mar 1, 2026Concise March 2026 monthly summary for apache/spark focusing on business value and technical achievements. Highlights include SHS multi-directory log support and efficiency improvements, reliability fixes in Spark Connect execution flow, Java 22+ compatibility, testing infrastructure enhancements, and on-demand metadata accuracy improvements.
14 Commits • 4 Features
Mar 1, 2026Concise March 2026 monthly summary for apache/spark focusing on business value and technical achievements. Highlights include SHS multi-directory log support and efficiency improvements, reliability fixes in Spark Connect execution flow, Java 22+ compatibility, testing infrastructure enhancements, and on-demand metadata accuracy improvements.
March 2026
February 2026
5 Commits • 2 Features
Feb 1, 2026February 2026: Delivered build-system hardening, testing framework modernization, and Web UI security fixes for apache/spark. Key improvements reduce release risk, boost test reliability, and preserve UI functionality under CSP changes.
February 2026
5 Commits • 2 Features
Feb 1, 2026February 2026: Delivered build-system hardening, testing framework modernization, and Web UI security fixes for apache/spark. Key improvements reduce release risk, boost test reliability, and preserve UI functionality under CSP changes.
January 2026
10 Commits • 2 Features
Jan 1, 20262026-01 Monthly Summary for apache/spark Key features delivered: - SparkConnectServer: YARN cluster mode support. Enables launching SparkConnectServer in YARN cluster mode to improve resource utilization and high availability for Hadoop-based deployments (commit 76f6c784a0c4c56078273501b2cf2268426f4602). - Platform upgrades and tooling hardening: Upgraded core build/runtime dependencies and associated tooling to improve security, compatibility, and CI reliability (SBT 1.12.0; Jetty/Jersey/Servlet updates; Node.js upgrade; shading adjustments and Javadoc fixes across related changes) (commits including 98874f0a376c1a818e9e412762ec70db37c464b1, d4bd663581e73fefec42ea460ceecbce594712e3, c270cc279ba4ebe9f5660826c0a6ff6b0f598ad0, 0e580b3ef71a9ed616518143eb9d8772daf71d6d). Major bugs fixed: - BlockInfoManager concurrency and stability fixes: Resolved race conditions between unlock and releaseAllLocksForTask to prevent assertion errors and to ensure correct lock accounting under concurrent usage (commits 752e8a1a7ee030ab8d0879c569754edce7b0b0f4 and 2bd4cf39781c50946df9daebbf14b2dacdb959ce). - Test stability improvements: Addressed flaky tests in RPC/Executor suites to improve CI reliability (commits a28133134c4dfba0f720be30e000cc66eb42051c, 9b3e203e1d026b7792d26cbcc66a387c8d37f18c). Overall impact and accomplishments: - Improved reliability and resilience of Spark deployments on Hadoop clusters through SparkConnectServer YARN support and robust lock management, enabling better resource utilization and HA. - Increased CI stability and faster feedback cycles via targeted flaky-test fixes and platform/tooling hardening. - Reduced risk in production by addressing concurrency-related assertions and stabilizing critical execution paths. Technologies/skills demonstrated: - Concurrency and multi-threading correctness in BlockInfoManager; race condition diagnosis and mitigation. - Build and dependency management across SBT, Jetty/Jersey/Servlet, Node.js, and shading rules; Javadoc generation stability. - Test stability engineering for RPC/Executor suites and overall CI reliability. - Spark internals understanding (SparkConnectServer, BlockInfoManager) and related release engineering.
10 Commits • 2 Features
Jan 1, 20262026-01 Monthly Summary for apache/spark Key features delivered: - SparkConnectServer: YARN cluster mode support. Enables launching SparkConnectServer in YARN cluster mode to improve resource utilization and high availability for Hadoop-based deployments (commit 76f6c784a0c4c56078273501b2cf2268426f4602). - Platform upgrades and tooling hardening: Upgraded core build/runtime dependencies and associated tooling to improve security, compatibility, and CI reliability (SBT 1.12.0; Jetty/Jersey/Servlet updates; Node.js upgrade; shading adjustments and Javadoc fixes across related changes) (commits including 98874f0a376c1a818e9e412762ec70db37c464b1, d4bd663581e73fefec42ea460ceecbce594712e3, c270cc279ba4ebe9f5660826c0a6ff6b0f598ad0, 0e580b3ef71a9ed616518143eb9d8772daf71d6d). Major bugs fixed: - BlockInfoManager concurrency and stability fixes: Resolved race conditions between unlock and releaseAllLocksForTask to prevent assertion errors and to ensure correct lock accounting under concurrent usage (commits 752e8a1a7ee030ab8d0879c569754edce7b0b0f4 and 2bd4cf39781c50946df9daebbf14b2dacdb959ce). - Test stability improvements: Addressed flaky tests in RPC/Executor suites to improve CI reliability (commits a28133134c4dfba0f720be30e000cc66eb42051c, 9b3e203e1d026b7792d26cbcc66a387c8d37f18c). Overall impact and accomplishments: - Improved reliability and resilience of Spark deployments on Hadoop clusters through SparkConnectServer YARN support and robust lock management, enabling better resource utilization and HA. - Increased CI stability and faster feedback cycles via targeted flaky-test fixes and platform/tooling hardening. - Reduced risk in production by addressing concurrency-related assertions and stabilizing critical execution paths. Technologies/skills demonstrated: - Concurrency and multi-threading correctness in BlockInfoManager; race condition diagnosis and mitigation. - Build and dependency management across SBT, Jetty/Jersey/Servlet, Node.js, and shading rules; Javadoc generation stability. - Test stability engineering for RPC/Executor suites and overall CI reliability. - Spark internals understanding (SparkConnectServer, BlockInfoManager) and related release engineering.
January 2026
December 2025
8 Commits • 1 Features
Dec 1, 2025December 2025 delivered targeted security hardening and dependency modernization for the Apache Spark project (apache/spark). Key work included securing the History page against XSS by escaping user and application names and adding corresponding tests, alongside Hive compatibility improvements and core dependency upgrades to support Hive 4.1 and improved stability. Infra and CI reliability were enhanced through workflow fixes and test updates, contributing to a more secure, compatible, and maintainable codebase.
December 2025
8 Commits • 1 Features
Dec 1, 2025December 2025 delivered targeted security hardening and dependency modernization for the Apache Spark project (apache/spark). Key work included securing the History page against XSS by escaping user and application names and adding corresponding tests, alongside Hive compatibility improvements and core dependency upgrades to support Hive 4.1 and improved stability. Infra and CI reliability were enhanced through workflow fixes and test updates, contributing to a more secure, compatible, and maintainable codebase.
November 2025
5 Commits • 3 Features
Nov 1, 2025November 2025: Strengthened CI stability, refreshed dependencies, and advanced readiness for Servlet 6.0 and Jetty upgrades across the Spark codebase. Delivered improvements span test infrastructure, dependency management, and cross-cutting utilities to enable broader reuse and smoother platform upgrades.
5 Commits • 3 Features
Nov 1, 2025November 2025: Strengthened CI stability, refreshed dependencies, and advanced readiness for Servlet 6.0 and Jetty upgrades across the Spark codebase. Delivered improvements span test infrastructure, dependency management, and cross-cutting utilities to enable broader reuse and smoother platform upgrades.
November 2025
October 2025
9 Commits • 1 Features
Oct 1, 2025Month: 2025-10 — Spark Connect-focused month delivering configurable JVM args, reliability fixes, and build/test hygiene. Business value: improved client configurability and stability, reduced CI flakiness, and cleaner dependency management. Highlights below.
October 2025
9 Commits • 1 Features
Oct 1, 2025Month: 2025-10 — Spark Connect-focused month delivering configurable JVM args, reliability fixes, and build/test hygiene. Business value: improved client configurability and stability, reduced CI flakiness, and cleaner dependency management. Highlights below.
September 2025
4 Commits
Sep 1, 2025September 2025: Delivered key test-stability improvements for Apache Spark with a focus on deterministic test execution and cross-platform reliability. Consolidated fixes across SparkConnectServiceSuite, SparkSessionE2ESuite, and AmmoniteTest enablement; replaced ForkJoinPool with a fixed thread pool to eliminate threading inheritance issues. Re-enabled AmmoniteTest tests in Maven builds to improve coverage and CI reliability. These changes reduced flaky failures, shortened feedback loops, and increased confidence in test results across macOS and Linux.
4 Commits
Sep 1, 2025September 2025: Delivered key test-stability improvements for Apache Spark with a focus on deterministic test execution and cross-platform reliability. Consolidated fixes across SparkConnectServiceSuite, SparkSessionE2ESuite, and AmmoniteTest enablement; replaced ForkJoinPool with a fixed thread pool to eliminate threading inheritance issues. Re-enabled AmmoniteTest tests in Maven builds to improve coverage and CI reliability. These changes reduced flaky failures, shortened feedback loops, and increased confidence in test results across macOS and Linux.
September 2025
July 2025
1 Commits
Jul 1, 2025July 2025 — Apache Spark: Stabilized SparkSessionE2ESuite interrupt handling to prevent test hangs, improving CI reliability and reducing flaky test runs. Refined the completion-detection logic for interrupt operations, addressing SPARK-50889. The change reduces indefinite waits and accelerates feedback for streaming-related changes. Demonstrated strong debugging, patch discipline, and collaboration with the test suite.
July 2025
1 Commits
Jul 1, 2025July 2025 — Apache Spark: Stabilized SparkSessionE2ESuite interrupt handling to prevent test hangs, improving CI reliability and reducing flaky test runs. Refined the completion-detection logic for interrupt operations, addressing SPARK-50889. The change reduces indefinite waits and accelerates feedback for streaming-related changes. Demonstrated strong debugging, patch discipline, and collaboration with the test suite.
Activity
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Quality Metrics
Correctness98.6%
Maintainability91.0%
Architecture92.6%
Performance91.8%
AI Usage31.4%
Skills & Technologies
Programming Languages
BashCSSHTMLJSONJavaJavaScriptNonePythonScalaShell
Technical Skills
API developmentApache SparkBig DataBootstrapBuild ConfigurationCI/CDCSSContinuous IntegrationData ProcessingDevOpsESLintGitHub ActionsHiveJavaJava development
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