joernio/joern
Oct 2024 – Mar 2026
18 Months active
Languages Used
JavaScalaPython
Technical Skills
AST ManipulationAbstract Syntax Trees (AST)Code AnalysisCode CleanupCode Property Graph (CPG)Compiler Development
Markus Lottmann
PROFILE
Markus Lottmann
Markus contributed to the joernio/joern repository by developing and refining static analysis tooling for multi-language codebases, focusing on Code Property Graph (CPG) generation and backend reliability. He enhanced Python and Kotlin frontends to improve parsing accuracy, error handling, and data flow analysis, using languages such as Scala, Java, and Python. Markus implemented lazy evaluation patterns for performance optimization, strengthened test coverage, and modernized API surfaces to support scalable analysis. His work addressed edge cases in language parsing, improved logging and observability, and ensured robust dependency management, resulting in a maintainable, reliable code analysis pipeline that supports complex real-world scenarios.
Overall Statistics
Feature vs Bugs
42%Features
Repository Contributions
32Total
Bugs
15
Commits
32
Features
11
Lines of code
5,526
Activity Months18
Your Network
24 peopleSame Organization
@shiftleft.io2
Shared Repositories
22
Work History
March 2026
4 Commits • 2 Features
Mar 1, 2026March 2026 monthly summary for joern team focusing on measurable business value and technical achievements.
4 Commits • 2 Features
Mar 1, 2026March 2026 monthly summary for joern team focusing on measurable business value and technical achievements.
March 2026
February 2026
3 Commits • 1 Features
Feb 1, 2026February 2026: Delivered enhanced test coverage for Code Property Graph (CPG) generation and Python AST parsing in joernio/joern, reinforcing reliability and reducing downstream risk. Implemented targeted tests to improve CPG accuracy (column numbers in binary/boolean operations and literal node properties) and expanded Python AST/parser coverage to include various forms of for statements and list expressions. No major bug fixes were required this month; the focus was on strengthening the test suite to enable safer refactoring and more robust analyses with PySrc2CPG alignment.
February 2026
3 Commits • 1 Features
Feb 1, 2026February 2026: Delivered enhanced test coverage for Code Property Graph (CPG) generation and Python AST parsing in joernio/joern, reinforcing reliability and reducing downstream risk. Implemented targeted tests to improve CPG accuracy (column numbers in binary/boolean operations and literal node properties) and expanded Python AST/parser coverage to include various forms of for statements and list expressions. No major bug fixes were required this month; the focus was on strengthening the test suite to enable safer refactoring and more robust analyses with PySrc2CPG alignment.
January 2026
3 Commits • 2 Features
Jan 1, 2026January 2026 (2026-01) monthly summary for joernio/joern. Delivered two features focused on readability, reliability, and observability in the codebase, with concrete commit-level changes that improve diagnostics and maintainability. The work supports faster debugging, reduces risk of CFG/CDG edge-related failures, and results in a cleaner, more maintainable Java-to-CPG pipeline.
3 Commits • 2 Features
Jan 1, 2026January 2026 (2026-01) monthly summary for joernio/joern. Delivered two features focused on readability, reliability, and observability in the codebase, with concrete commit-level changes that improve diagnostics and maintainability. The work supports faster debugging, reduces risk of CFG/CDG edge-related failures, and results in a cleaner, more maintainable Java-to-CPG pipeline.
January 2026
December 2025
1 Commits
Dec 1, 2025December 2025 — Joern (joernio/joern): Delivered a critical correctness improvement to the Code Property Graph (CPG) for match statements. This fixes incomplete CFG construction by ensuring case bodies are included in the CFG and by representing match patterns and guards as JUMP_TARGETS in the AST, aligning with CfgCreator expectations and enabling more precise program analysis. This work was implemented in the pysrc2cpg effort and referenced in PR #5720, with commit 2f5a1378cfcf6c227703b01362fe86c4158bdd40.
December 2025
1 Commits
Dec 1, 2025December 2025 — Joern (joernio/joern): Delivered a critical correctness improvement to the Code Property Graph (CPG) for match statements. This fixes incomplete CFG construction by ensuring case bodies are included in the CFG and by representing match patterns and guards as JUMP_TARGETS in the AST, aligning with CfgCreator expectations and enabling more precise program analysis. This work was implemented in the pysrc2cpg effort and referenced in PR #5720, with commit 2f5a1378cfcf6c227703b01362fe86c4158bdd40.
November 2025
1 Commits • 1 Features
Nov 1, 2025November 2025: Joern development—delivered a robust Python parser indentation feature and strengthened code analysis reliability in joernio/joern. Focused on improving Python indentation handling with mixed spaces and tabs, expanding test coverage, and fixing a parser grammar tab-handling bug to support more than two tabs. These changes reduce parsing errors, improve accuracy of code property graphs, and enable better support for real-world Python code bases, enhancing overall product reliability and developer productivity.
1 Commits • 1 Features
Nov 1, 2025November 2025: Joern development—delivered a robust Python parser indentation feature and strengthened code analysis reliability in joernio/joern. Focused on improving Python indentation handling with mixed spaces and tabs, expanding test coverage, and fixing a parser grammar tab-handling bug to support more than two tabs. These changes reduce parsing errors, improve accuracy of code property graphs, and enable better support for real-world Python code bases, enhancing overall product reliability and developer productivity.
November 2025
October 2025
1 Commits
Oct 1, 2025October 2025: Focused on stabilizing Kotlin-to-CPG conversion under partial type information. Implemented a targeted refactor for SAM interface handling to prevent NoSuchElementException and improved robustness of parsing lambda expressions used as arguments in the Kotlin to CPG converter. All changes contributed to the joernio/joern repository with a targeted fix under partial type data.
October 2025
1 Commits
Oct 1, 2025October 2025: Focused on stabilizing Kotlin-to-CPG conversion under partial type information. Implemented a targeted refactor for SAM interface handling to prevent NoSuchElementException and improved robustness of parsing lambda expressions used as arguments in the Kotlin to CPG converter. All changes contributed to the joernio/joern repository with a targeted fix under partial type data.
September 2025
3 Commits
Sep 1, 2025September 2025 monthly summary for joernio/joern: Delivered targeted stability and reliability improvements across the Gradle build and Kotlin-to-CPG frontend, focusing on dependency resolution, error logging, and null pointer handling. These changes reduce downtime and improve developer debugging experience. No new user-facing features; work focused on robustness and maintainability.
3 Commits
Sep 1, 2025September 2025 monthly summary for joernio/joern: Delivered targeted stability and reliability improvements across the Gradle build and Kotlin-to-CPG frontend, focusing on dependency resolution, error logging, and null pointer handling. These changes reduce downtime and improve developer debugging experience. No new user-facing features; work focused on robustness and maintainability.
September 2025
August 2025
1 Commits
Aug 1, 2025Monthly summary for 2025-08: Focused on improving reliability of the CPG converter in joernio/joern by hardening error handling for parse failures and expanding test coverage. The key improvement ensures a File node is created when parsing fails, using the file content when enabled or an empty string otherwise; this enhances debugging and the integrity of the generated Code Property Graph.
August 2025
1 Commits
Aug 1, 2025Monthly summary for 2025-08: Focused on improving reliability of the CPG converter in joernio/joern by hardening error handling for parse failures and expanding test coverage. The key improvement ensures a File node is created when parsing fails, using the file content when enabled or an empty string otherwise; this enhances debugging and the integrity of the generated Code Property Graph.
July 2025
1 Commits
Jul 1, 2025July 2025 performance summary for repository joernio/joern. Focused on stability and data integrity in the Kotlin2CPG frontend. Delivered a critical bug fix to ensure complete file content retrieval, eliminating truncation and improving accuracy of downstream analysis. This work strengthens the reliability of code graph generation and reduces rework due to incomplete content.
1 Commits
Jul 1, 2025July 2025 performance summary for repository joernio/joern. Focused on stability and data integrity in the Kotlin2CPG frontend. Delivered a critical bug fix to ensure complete file content retrieval, eliminating truncation and improving accuracy of downstream analysis. This work strengthens the reliability of code graph generation and reduces rework due to incomplete content.
July 2025
June 2025
1 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for joernio/joern. Key deliverable this month was a performance-driven refactor of location information retrieval. The team implemented lazy computation for location details by introducing a LocationInfo trait and LocationCreator, replacing the older NewLocation concept. This change reduces unnecessary computation and speeds up analysis runs on larger codebases. There were no major bug fixes this month; the focus was on performance optimization and API modernization. Overall impact includes faster location data retrieval for Joern analyses and improved scalability of location metadata handling. Technologies/skills demonstrated include trait-based design, lazy evaluation patterns, and API surface refactoring to enable scalable, on-demand computation.
June 2025
1 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for joernio/joern. Key deliverable this month was a performance-driven refactor of location information retrieval. The team implemented lazy computation for location details by introducing a LocationInfo trait and LocationCreator, replacing the older NewLocation concept. This change reduces unnecessary computation and speeds up analysis runs on larger codebases. There were no major bug fixes this month; the focus was on performance optimization and API modernization. Overall impact includes faster location data retrieval for Joern analyses and improved scalability of location metadata handling. Technologies/skills demonstrated include trait-based design, lazy evaluation patterns, and API surface refactoring to enable scalable, on-demand computation.
May 2025
1 Commits • 1 Features
May 1, 2025In May 2025, delivered a focused observability improvement for the JavaScript source-to-code property graph frontend in joernio/joern. The change enhances error reporting during file filtering by including the failing file path in logs and reducing the log level from error to warn, clarifying issues without increasing log verbosity. Impact and delivery details: - Implemented through commit 887651d21007a0e5496a4463c1aef599cebba661 ([jssrc2cpg] Improve log message for exceptions in file filtering. (#5518)). - Result: clearer, actionable logs with reduced log noise, enabling faster triage of file-filtering failures. Overall impact: - Improved observability for the JS s2cpg frontend, leading to faster root-cause analysis with minimal performance impact. - Aligns with established logging practices and prepares the ground for future enhancements in error handling and diagnostics. Technologies/skills demonstrated: - JavaScript frontend debugging and observability, exception handling, and log-level tuning. - Collaborated on a targeted fix within the jssrc2cpg module to improve maintainability and operational clarity.
1 Commits • 1 Features
May 1, 2025In May 2025, delivered a focused observability improvement for the JavaScript source-to-code property graph frontend in joernio/joern. The change enhances error reporting during file filtering by including the failing file path in logs and reducing the log level from error to warn, clarifying issues without increasing log verbosity. Impact and delivery details: - Implemented through commit 887651d21007a0e5496a4463c1aef599cebba661 ([jssrc2cpg] Improve log message for exceptions in file filtering. (#5518)). - Result: clearer, actionable logs with reduced log noise, enabling faster triage of file-filtering failures. Overall impact: - Improved observability for the JS s2cpg frontend, leading to faster root-cause analysis with minimal performance impact. - Aligns with established logging practices and prepares the ground for future enhancements in error handling and diagnostics. Technologies/skills demonstrated: - JavaScript frontend debugging and observability, exception handling, and log-level tuning. - Collaborated on a targeted fix within the jssrc2cpg module to improve maintainability and operational clarity.
May 2025
April 2025
1 Commits
Apr 1, 2025April 2025 monthly summary for joernio/joern: Reverted ERB file parsing in the Ruby frontend to enable adjustments to backend passes and stabilize frontend-backend integration. This release removes ERB parsing capabilities introduced recently, via the revert commit df60f873d30ab233b88c1d00e1e5ab3d5f210898, to align frontend behavior with backend refactors and reduce risk. Focused on maintaining core functionality while preparing the codebase for upcoming backend changes, improving maintainability and predictability of release outcomes.
April 2025
1 Commits
Apr 1, 2025April 2025 monthly summary for joernio/joern: Reverted ERB file parsing in the Ruby frontend to enable adjustments to backend passes and stabilize frontend-backend integration. This release removes ERB parsing capabilities introduced recently, via the revert commit df60f873d30ab233b88c1d00e1e5ab3d5f210898, to align frontend behavior with backend refactors and reduce risk. Focused on maintaining core functionality while preparing the codebase for upcoming backend changes, improving maintainability and predictability of release outcomes.
March 2025
1 Commits
Mar 1, 2025March 2025 monthly summary for joernio/joern: Implemented a robustness improvement for Kotlin SAM interface lookup by replacing manual parameter resolution with getArgumentsWithConversion. This fixes incorrect handling of lambdas passed into generic vararg functions and aligns interface resolution with a central, reliable path. Change reduces edge-case failures and enhances the reliability of Kotlin interop within Joern's static code analysis.
1 Commits
Mar 1, 2025March 2025 monthly summary for joernio/joern: Implemented a robustness improvement for Kotlin SAM interface lookup by replacing manual parameter resolution with getArgumentsWithConversion. This fixes incorrect handling of lambdas passed into generic vararg functions and aligns interface resolution with a central, reliable path. Change reduces edge-case failures and enhances the reliability of Kotlin interop within Joern's static code analysis.
March 2025
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 Monthly Summary — joernio/joern Key feature delivered: - Unique full names for redefined Python methods in the method conversion pipeline. This refactor correctly handles function redefinitions, improving accuracy of code analysis for Python projects with overlapping function names. Commit: 014f809e03f0c89644cc1da692d64565e6f6b6ee (markus/handleFunctionRedefinition #5276). Major bugs fixed: - No standalone major bug fixes recorded this month beyond the refactor aimed at correctness in Python method redefinition handling. Overall impact and accomplishments: - Improved analysis reliability for Python code within the project, reducing false positives related to function redefinitions and increasing trust in code insights. - Strengthened the method conversion pipeline with a robust naming strategy, aligning with product goals for accurate multi-language code analysis. Technologies/skills demonstrated: - Refactoring and naming strategy for code analysis pipelines - Static analysis and method conversion for Python projects - Version-controlled design with traceable commits (e.g., commit 014f809e03f0c89644cc1da692d64565e6f6b6ee) - Cross-language analysis considerations within the Joern project Business value: - Higher accuracy in code analysis translates to faster, more reliable insights for developers and customers working with Python codebases, supporting better decision-making and risk assessment.
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 Monthly Summary — joernio/joern Key feature delivered: - Unique full names for redefined Python methods in the method conversion pipeline. This refactor correctly handles function redefinitions, improving accuracy of code analysis for Python projects with overlapping function names. Commit: 014f809e03f0c89644cc1da692d64565e6f6b6ee (markus/handleFunctionRedefinition #5276). Major bugs fixed: - No standalone major bug fixes recorded this month beyond the refactor aimed at correctness in Python method redefinition handling. Overall impact and accomplishments: - Improved analysis reliability for Python code within the project, reducing false positives related to function redefinitions and increasing trust in code insights. - Strengthened the method conversion pipeline with a robust naming strategy, aligning with product goals for accurate multi-language code analysis. Technologies/skills demonstrated: - Refactoring and naming strategy for code analysis pipelines - Static analysis and method conversion for Python projects - Version-controlled design with traceable commits (e.g., commit 014f809e03f0c89644cc1da692d64565e6f6b6ee) - Cross-language analysis considerations within the Joern project Business value: - Higher accuracy in code analysis translates to faster, more reliable insights for developers and customers working with Python codebases, supporting better decision-making and risk assessment.
January 2025
2 Commits
Jan 1, 2025January 2025 monthly summary for joernio/joern: Focused on stability and developer experience, delivering critical fixes to Kotlin-to-CPG conversion and Maven dependency debugging. These changes improve accuracy of the Code Property Graph for Kotlin code, hardening the pipeline against edge cases, and provide clearer debugging guidance for build issues. Result: more reliable static analysis outputs and faster issue resolution for downstream users.
2 Commits
Jan 1, 2025January 2025 monthly summary for joernio/joern: Focused on stability and developer experience, delivering critical fixes to Kotlin-to-CPG conversion and Maven dependency debugging. These changes improve accuracy of the Code Property Graph for Kotlin code, hardening the pipeline against edge cases, and provide clearer debugging guidance for build issues. Result: more reliable static analysis outputs and faster issue resolution for downstream users.
January 2025
December 2024
1 Commits • 1 Features
Dec 1, 2024December 2024: Delivered targeted Python-to-CPG frontend improvements for the joern project to improve the accuracy and granularity of the Code Property Graph representations for Python code. Key work centered on correct handling of class-body variable writes and exposing per-method topLevelExpressions, enabling finer-grained analysis and more reliable graph construction. These changes reduce false positives in member writes, improve downstream analytics, and better support Python codebases in future analyses.
December 2024
1 Commits • 1 Features
Dec 1, 2024December 2024: Delivered targeted Python-to-CPG frontend improvements for the joern project to improve the accuracy and granularity of the Code Property Graph representations for Python code. Key work centered on correct handling of class-body variable writes and exposing per-method topLevelExpressions, enabling finer-grained analysis and more reliable graph construction. These changes reduce false positives in member writes, improve downstream analytics, and better support Python codebases in future analyses.
November 2024
2 Commits
Nov 1, 2024Month 2024-11: Focused on stability and data-flow accuracy in core graph components. Delivered two critical bug fixes in the joernio/joern project: Kotlin2CPG frontend resource-based classpath handling and Python code property graph variable disambiguation. These changes reduce runtime classpath flakiness and improve data-flow linking, enabling more reliable code queries and analysis for customers.
2 Commits
Nov 1, 2024Month 2024-11: Focused on stability and data-flow accuracy in core graph components. Delivered two critical bug fixes in the joernio/joern project: Kotlin2CPG frontend resource-based classpath handling and Python code property graph variable disambiguation. These changes reduce runtime classpath flakiness and improve data-flow linking, enabling more reliable code queries and analysis for customers.
November 2024
October 2024
4 Commits • 1 Features
Oct 1, 20242024-10 monthly summary for joern. Delivered Kotlin-to-CPG frontend enhancements and a critical Java-to-CPG bug fix, improving accuracy of CPG representations, expanding test coverage, and reducing technical debt. These efforts enhance Kotlin and Java source analysis, enabling more reliable downstream tooling and faster development cycles.
October 2024
4 Commits • 1 Features
Oct 1, 20242024-10 monthly summary for joern. Delivered Kotlin-to-CPG frontend enhancements and a critical Java-to-CPG bug fix, improving accuracy of CPG representations, expanding test coverage, and reducing technical debt. These efforts enhance Kotlin and Java source analysis, enabling more reliable downstream tooling and faster development cycles.
Activity
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Quality Metrics
Correctness89.6%
Maintainability86.0%
Architecture86.8%
Performance80.0%
AI Usage21.8%
Skills & Technologies
Programming Languages
JavaPythonScala
Technical Skills
API DesignAST ManipulationAbstract Syntax Trees (AST)Backend DevelopmentBuild ManagementBuild ToolingBuild ToolsCPGCode AnalysisCode CleanupCode ParsingCode Property Graph (CPG)Code Property GraphsCode RefactoringCode Reversion
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline