mozilla/treeherder
Nov 2024 – Oct 2025
10 Months active
Languages Used
PythonJavaScriptSQLYAMLJSXShell
Technical Skills
Backend DevelopmentTestingFrontend DevelopmentJavaScript DevelopmentFront End DevelopmentReact
Gregory Mierzwinski
PROFILE
Gregory Mierzwinski
Greg Mierzwinski contributed to mozilla/treeherder by building and enhancing performance monitoring, alerting, and data integration features across backend and frontend systems. He implemented telemetry-driven alerting, expanded data replication pipelines, and improved performance regression detection using Python, JavaScript, and BigQuery. His work included schema migrations, API optimizations, and UI enhancements in React to streamline developer workflows and increase observability. Greg addressed platform naming consistency, access control, and job tracking, ensuring reliable test routing and accurate dashboard data. Through careful debugging, system integration, and code refactoring, he delivered robust solutions that improved reliability, traceability, and the overall quality of performance analytics.
Overall Statistics
Feature vs Bugs
67%Features
Repository Contributions
15Total
Bugs
4
Commits
15
Features
8
Lines of code
2,290
Activity Months10
Your Network
374 people
Work History
October 2025
1 Commits • 1 Features
Oct 1, 2025Month: 2025-10 – Summary of technical delivery and impact for mozilla/treeherder focused on performance observability and alerting improvements. Key feature delivered: Enhanced Performance Monitoring: Telemetry Probes for Auto-Perf-Sheriffing. This work adds three new telemetry probe names to the existing initial probes tuple to enable more granular alerting on performance regressions within the auto-perf-sheriffing system. Major bugs fixed: No major bugs fixed this month. Overall impact and accomplishments: Strengthened production observability and alerting for performance regressions, enabling faster detection and remediation in the Auto-Perf-Sheriffing pipeline. The change supports data-driven decisions for performance stability and reduces MTTR for regression incidents. Technologies/skills demonstrated: Telemetry instrumentation, performance monitoring, observability enhancements, repository: mozilla/treeherder, code instrumentation, collaboration across performance tooling teams.
1 Commits • 1 Features
Oct 1, 2025Month: 2025-10 – Summary of technical delivery and impact for mozilla/treeherder focused on performance observability and alerting improvements. Key feature delivered: Enhanced Performance Monitoring: Telemetry Probes for Auto-Perf-Sheriffing. This work adds three new telemetry probe names to the existing initial probes tuple to enable more granular alerting on performance regressions within the auto-perf-sheriffing system. Major bugs fixed: No major bugs fixed this month. Overall impact and accomplishments: Strengthened production observability and alerting for performance regressions, enabling faster detection and remediation in the Auto-Perf-Sheriffing pipeline. The change supports data-driven decisions for performance stability and reduces MTTR for regression incidents. Technologies/skills demonstrated: Telemetry instrumentation, performance monitoring, observability enhancements, repository: mozilla/treeherder, code instrumentation, collaboration across performance tooling teams.
October 2025
July 2025
2 Commits • 1 Features
Jul 1, 2025For 2025-07, delivered key improvements in mozilla/treeherder focusing on alerting reliability and API correctness. Highlights include enabling Performance Test Alerting in monitor-only mode with email notifications visible on Perfherder's Monitored Alerts and enabling email notifications for all alerts via a new alertNotifyEmails field. Addressed API reliability by removing a problematic OR-filter on tables with many-to-* associations to fix duplicate alert summaries. Commits include 0ce27a5928079926b32c880dfc2b9548a045fb9f (#8670) and 45bc1498d89feb07722483c3ac28c0d00b76cad4 (#8859). The work improves alert visibility, reduces noise from duplicate summaries, and expands test coverage with new fixtures and a dedicated test case.
July 2025
2 Commits • 1 Features
Jul 1, 2025For 2025-07, delivered key improvements in mozilla/treeherder focusing on alerting reliability and API correctness. Highlights include enabling Performance Test Alerting in monitor-only mode with email notifications visible on Perfherder's Monitored Alerts and enabling email notifications for all alerts via a new alertNotifyEmails field. Addressed API reliability by removing a problematic OR-filter on tables with many-to-* associations to fix duplicate alert summaries. Commits include 0ce27a5928079926b32c880dfc2b9548a045fb9f (#8670) and 45bc1498d89feb07722483c3ac28c0d00b76cad4 (#8859). The work improves alert visibility, reduces noise from duplicate summaries, and expands test coverage with new fixtures and a dedicated test case.
June 2025
4 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for mozilla/treeherder: Delivered a prototype telemetry alerting feature for perf_sheriff with mozdetect integration, enabling early detection of telemetry changes and storing results in new PerformanceTelemetryAlert and PerformanceTelemetryAlertSummary tables. Implemented safeguards and deployment controls to minimize risk in production while enabling richer telemetry insights.
4 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for mozilla/treeherder: Delivered a prototype telemetry alerting feature for perf_sheriff with mozdetect integration, enabling early detection of telemetry changes and storing results in new PerformanceTelemetryAlert and PerformanceTelemetryAlertSummary tables. Implemented safeguards and deployment controls to minimize risk in production while enabling richer telemetry insights.
June 2025
May 2025
1 Commits • 1 Features
May 1, 2025May 2025: Implemented Lando Commit Integration and Job Status Tracking in mozilla/treeherder. Introduced support for using Lando commit IDs as a parameter, converting them to revisions, and displaying/tracking associated jobs. Added URL helpers and robust job view polling for Lando job statuses. Fixed Bug 1964784 by adding the parameter for Lando IDs and converting it to a revision, strengthening end-to-end traceability and developer workflow. This work improves developer productivity, reduces triage time, and enhances release visibility by providing unified job tracking from commit to CI results. Technologies demonstrated: parameter handling, revision conversion, frontend polling, URL helpers, and repository integration patterns.
May 2025
1 Commits • 1 Features
May 1, 2025May 2025: Implemented Lando Commit Integration and Job Status Tracking in mozilla/treeherder. Introduced support for using Lando commit IDs as a parameter, converting them to revisions, and displaying/tracking associated jobs. Added URL helpers and robust job view polling for Lando job statuses. Fixed Bug 1964784 by adding the parameter for Lando IDs and converting it to a revision, strengthening end-to-end traceability and developer workflow. This work improves developer productivity, reduces triage time, and enhances release visibility by providing unified job tracking from commit to CI results. Technologies demonstrated: parameter handling, revision conversion, frontend polling, URL helpers, and repository integration patterns.
April 2025
1 Commits
Apr 1, 2025April 2025 monthly summary for mozilla/treeherder: Stabilized shippable platform identification by correcting the A55 naming mapping. Key bug fix ensures the android-hw-a55-14-0-aarch64-shippable and android-hw-a55-14-0-aarch64 entries align with the expected platform constants, eliminating a naming misclassification risk. This change improves test routing, CI dashboards, and data reliability for A55 shippable tests. Impact: improved accuracy, reduced misrouting risk, smoother test execution. Technologies/skills demonstrated: debugging platform constants, Android hardware naming conventions, commit-based fixes, version control, code review.
1 Commits
Apr 1, 2025April 2025 monthly summary for mozilla/treeherder: Stabilized shippable platform identification by correcting the A55 naming mapping. Key bug fix ensures the android-hw-a55-14-0-aarch64-shippable and android-hw-a55-14-0-aarch64 entries align with the expected platform constants, eliminating a naming misclassification risk. This change improves test routing, CI dashboards, and data reliability for A55 shippable tests. Impact: improved accuracy, reduced misrouting risk, smoother test execution. Technologies/skills demonstrated: debugging platform constants, Android hardware naming conventions, commit-based fixes, version control, code review.
April 2025
March 2025
2 Commits • 1 Features
Mar 1, 2025March 2025: Delivered key performance-related improvements to mozilla/treeherder, focusing on clearer alerting and accurate performance data for dashboards. Implemented the Improve Performance Regression Alerts feature and fixed the Performance Query Field Separation bug, enhancing incident response and data reliability.
March 2025
2 Commits • 1 Features
Mar 1, 2025March 2025: Delivered key performance-related improvements to mozilla/treeherder, focusing on clearer alerting and accurate performance data for dashboards. Implemented the Improve Performance Regression Alerts feature and fixed the Performance Query Field Separation bug, enhancing incident response and data reliability.
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 — Focused on strengthening Treeherder's performance monitoring and alerting capabilities by delivering backend schema improvements for advanced detection techniques and telemetry-driven alerts, alongside refactoring for maintainability. This work enables earlier detection of performance regressions, richer telemetry analytics, and faster remediation, driving improved reliability and user experience.
1 Commits • 1 Features
Feb 1, 2025February 2025 — Focused on strengthening Treeherder's performance monitoring and alerting capabilities by delivering backend schema improvements for advanced detection techniques and telemetry-driven alerts, alongside refactoring for maintainability. This work enables earlier detection of performance regressions, richer telemetry analytics, and faster remediation, driving improved reliability and user experience.
February 2025
January 2025
1 Commits
Jan 1, 2025January 2025 monthly summary for mozilla/treeherder focused on security and quality of bug reporting from alerts. Implemented a targeted access-control improvement preventing filing of new bugs directly from the Alerts view unless the user has isStaff = true. The UI now enforces this RBAC check, reducing unauthorized bug reports and improving triage quality. The change is tracked as Bug 1942662, implemented with a UI-level conditional in the Alerts component, committed as bd5f93ff4321f2a6c46df83da7af25fb6141c074 ("Bug 1942662 - Add a check for filing bugs in the alerts view. (#8439)").
January 2025
1 Commits
Jan 1, 2025January 2025 monthly summary for mozilla/treeherder focused on security and quality of bug reporting from alerts. Implemented a targeted access-control improvement preventing filing of new bugs directly from the Alerts view unless the user has isStaff = true. The UI now enforces this RBAC check, reducing unauthorized bug reports and improving triage quality. The change is tracked as Bug 1942662, implemented with a UI-level conditional in the Alerts component, committed as bd5f93ff4321f2a6c46df83da7af25fb6141c074 ("Bug 1942662 - Add a check for filing bugs in the alerts view. (#8439)").
December 2024
1 Commits • 1 Features
Dec 1, 2024December 2024 — mozilla/treeherder: Delivered Mozperftest harness recognition and profiling button integration. This enables mozperftest-based jobs to display the profiling button in the Treeherder UI, improving usability and visibility for performance testing and profiling workflows. The work is aligned with Bug 1936640 and references commit 81c3addaea4ed58f7812c1c8d27a910c217c4b8f ("Bug 1936640 - Add mozperftest harness as a valid harness to show profiling button on. (#8350)").
1 Commits • 1 Features
Dec 1, 2024December 2024 — mozilla/treeherder: Delivered Mozperftest harness recognition and profiling button integration. This enables mozperftest-based jobs to display the profiling button in the Treeherder UI, improving usability and visibility for performance testing and profiling workflows. The work is aligned with Bug 1936640 and references commit 81c3addaea4ed58f7812c1c8d27a910c217c4b8f ("Bug 1936640 - Add mozperftest harness as a valid harness to show profiling button on. (#8350)").
December 2024
November 2024
1 Commits • 1 Features
Nov 1, 2024Month 2024-11: Delivered expanded replicate data collection for applink-startup tests on mozilla-central, extending replication coverage from try repos and speedometer3 to a new test suite. Implemented via enabling replicates for applink-startup tests (Bug 1932211) with commit 5269aeda9cc30626f7df81a427e0760782c54717. Key business value: broader test data coverage across mozilla-central improves visibility into test outcomes, enables earlier detection of regressions, and informs performance improvements. Technical accomplishments: expanded data replication pipeline, integrated applink-startup test coverage into treeherder data flow, demonstrated effective version-control discipline and cross-repo collaboration.
November 2024
1 Commits • 1 Features
Nov 1, 2024Month 2024-11: Delivered expanded replicate data collection for applink-startup tests on mozilla-central, extending replication coverage from try repos and speedometer3 to a new test suite. Implemented via enabling replicates for applink-startup tests (Bug 1932211) with commit 5269aeda9cc30626f7df81a427e0760782c54717. Key business value: broader test data coverage across mozilla-central improves visibility into test outcomes, enables earlier detection of regressions, and informs performance improvements. Technical accomplishments: expanded data replication pipeline, integrated applink-startup test coverage into treeherder data flow, demonstrated effective version-control discipline and cross-repo collaboration.
Activity
Loading activity data...
Quality Metrics
Correctness87.4%
Maintainability88.0%
Architecture83.4%
Performance80.0%
AI Usage20.0%
Skills & Technologies
Programming Languages
JSXJavaScriptPythonSQLShellYAML
Technical Skills
API DevelopmentBackend DevelopmentBigQueryCloud InfrastructureDatabase DesignDatabase ManagementDatabase Query OptimizationDebuggingDevOpsDjangoDockerFront End DevelopmentFrontend DevelopmentJavaScriptJavaScript Development
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline