erlang/otp
Jun 2024 – Feb 2026
14 Months active
Languages Used
C++CErlangPerlShellMakefileAssemblyJSON
Technical Skills
JIT compilationcross-platform developmentdebugginglow-level programmingC programmingcompiler design
John Högberg
PROFILE
John Högberg
John contributed extensively to the erlang/otp repository, focusing on runtime stability, build automation, and core system enhancements. Over 14 months, he delivered features such as cross-platform JIT debugging, Docker-based development environments, and memory-efficient VM APIs. His work involved deep changes in C, Erlang, and C++, including compiler warning suppression macros, ARM/AArch64 JIT improvements, and robust error handling in the runtime. John also upgraded core libraries like AsmJit, improved static analysis reliability, and streamlined CI/CD workflows. His engineering consistently addressed maintainability, cross-platform compatibility, and developer productivity, demonstrating strong expertise in low-level programming, build systems, and system programming.
Overall Statistics
Feature vs Bugs
57%Features
Repository Contributions
40Total
Bugs
13
Commits
40
Features
17
Lines of code
13,523,702
Activity Months14
Your Network
186 peopleShared Repositories
169
Work History
February 2026
2 Commits • 1 Features
Feb 1, 2026February 2026 monthly summary for erlang/otp focused on core library improvements and build stability enhancements. Delivered a major AsmJit upgrade with ARM/AArch64 enhancements and implemented a build-stabilizing change to ignore core files in TTF directories to reduce test noise.
2 Commits • 1 Features
Feb 1, 2026February 2026 monthly summary for erlang/otp focused on core library improvements and build stability enhancements. Delivered a major AsmJit upgrade with ARM/AArch64 enhancements and implemented a build-stabilizing change to ignore core files in TTF directories to reduce test noise.
February 2026
January 2026
3 Commits • 2 Features
Jan 1, 2026January 2026 (2026-01) monthly summary for erlang/otp: delivered documentation improvements and runtime build simplification, with strong focus on maintainability, versioning accuracy, and build cleanliness. No major bug fixes documented this month; changes are geared toward improved developer experience and release readiness.
January 2026
3 Commits • 2 Features
Jan 1, 2026January 2026 (2026-01) monthly summary for erlang/otp: delivered documentation improvements and runtime build simplification, with strong focus on maintainability, versioning accuracy, and build cleanliness. No major bug fixes documented this month; changes are geared toward improved developer experience and release readiness.
November 2025
5 Commits • 3 Features
Nov 1, 2025Month: 2025-11 Concise monthly summary for Erlang/OTP contributions (2025-11). Key features delivered: - Developer Experience Improvements and CI/CD for Erlang/OTP: Consolidated development tooling, development container config, Emacs settings, and GitHub workflows to streamline CI/CD, plus scripts to build/manage Docker images. Commits: 776f654bda56b09a9ed4158f318015a406c29597; 40d203c5050fa72a05f37bbd0b906b493d3ae823. - Logger configuration consistency improvement: Ensure configurations returned by get_handler_config/0 and handler IDs from get_handler_ids/0 are sorted for deterministic and predictable logger behavior. Commit: b27196b6cde54ecaec6de743519c55841cf578a8. - Runtime performance optimization: on-heap bitstrings in binary_to_term: Relax the trapping logic for on-heap bitstrings to improve memory management and runtime performance. Commit: 20b8a11c3ce52dece0396cbfa370f32d9abd555f. - File handling enhancement: Zstd compression support: Add support for zstd compression in file handling to enable reading/writing zstd-compressed files. Commit: fc327ea18b5eb8499c4329b54aa39d17fab27d2a. Major bugs fixed: - erts: Fix use-before-initialization bug and related errors. Commit: 776f654bda56b09a9ed4158f318015a406c29597. - Logger configuration ordering bug: Ensure deterministic ordering for get_handler_config/0 and get_handler_ids/0 outputs. Commit: b27196b6cde54ecaec6de743519c55841cf578a8. Overall impact and accomplishments: - Significantly improved developer onboarding and CI/CD reliability through unified tooling, containerized dev environments, and streamlined workflows. - Achieved measurable runtime improvements by optimizing on-heap bitstring handling, reducing memory pressure during binary_term operations. - Expanded data storage/retrieval capabilities with Zstd support, enabling efficient handling of compressed data. - Increased logging stability and predictability, reducing operational toil and incidental errors in production. Technologies/skills demonstrated: - Docker-based development environments, container tooling, and Docker image management scripts. - GitHub Actions workflows for CI/CD automation. - Erlang/OTP internals: erts initialization behavior, memory management optimizations, and changes to binary_to_term. - Data compression integration with Zstd.
5 Commits • 3 Features
Nov 1, 2025Month: 2025-11 Concise monthly summary for Erlang/OTP contributions (2025-11). Key features delivered: - Developer Experience Improvements and CI/CD for Erlang/OTP: Consolidated development tooling, development container config, Emacs settings, and GitHub workflows to streamline CI/CD, plus scripts to build/manage Docker images. Commits: 776f654bda56b09a9ed4158f318015a406c29597; 40d203c5050fa72a05f37bbd0b906b493d3ae823. - Logger configuration consistency improvement: Ensure configurations returned by get_handler_config/0 and handler IDs from get_handler_ids/0 are sorted for deterministic and predictable logger behavior. Commit: b27196b6cde54ecaec6de743519c55841cf578a8. - Runtime performance optimization: on-heap bitstrings in binary_to_term: Relax the trapping logic for on-heap bitstrings to improve memory management and runtime performance. Commit: 20b8a11c3ce52dece0396cbfa370f32d9abd555f. - File handling enhancement: Zstd compression support: Add support for zstd compression in file handling to enable reading/writing zstd-compressed files. Commit: fc327ea18b5eb8499c4329b54aa39d17fab27d2a. Major bugs fixed: - erts: Fix use-before-initialization bug and related errors. Commit: 776f654bda56b09a9ed4158f318015a406c29597. - Logger configuration ordering bug: Ensure deterministic ordering for get_handler_config/0 and get_handler_ids/0 outputs. Commit: b27196b6cde54ecaec6de743519c55841cf578a8. Overall impact and accomplishments: - Significantly improved developer onboarding and CI/CD reliability through unified tooling, containerized dev environments, and streamlined workflows. - Achieved measurable runtime improvements by optimizing on-heap bitstring handling, reducing memory pressure during binary_term operations. - Expanded data storage/retrieval capabilities with Zstd support, enabling efficient handling of compressed data. - Increased logging stability and predictability, reducing operational toil and incidental errors in production. Technologies/skills demonstrated: - Docker-based development environments, container tooling, and Docker image management scripts. - GitHub Actions workflows for CI/CD automation. - Erlang/OTP internals: erts initialization behavior, memory management optimizations, and changes to binary_to_term. - Data compression integration with Zstd.
November 2025
October 2025
2 Commits • 1 Features
Oct 1, 2025Monthly summary for 2025-10: Focused on stability and reliability of the Erlang/OTP runtime. Delivered a stability improvement by updating preloaded modules, replacing binary beam files to ensure the latest compiled versions are loaded at startup. This work, implemented via two commits (52c6beb082fe89f318c32da5b1a0f9a7e0890cda; 130fdee41e8b8a40f242eaf0cf5b4d4f99e366dd), reduces the risk of runtime inconsistencies and aligns runtime artifacts with the current release build. Major bugs fixed: none reported this month; the emphasis was on stability and artifact integrity. Overall impact: higher production reliability, smoother deployments, and clearer traceability of changes. Technologies/skills demonstrated: Erlang/OTP module loading, binary artifact management, build/release engineering, and repository maintenance.
October 2025
2 Commits • 1 Features
Oct 1, 2025Monthly summary for 2025-10: Focused on stability and reliability of the Erlang/OTP runtime. Delivered a stability improvement by updating preloaded modules, replacing binary beam files to ensure the latest compiled versions are loaded at startup. This work, implemented via two commits (52c6beb082fe89f318c32da5b1a0f9a7e0890cda; 130fdee41e8b8a40f242eaf0cf5b4d4f99e366dd), reduces the risk of runtime inconsistencies and aligns runtime artifacts with the current release build. Major bugs fixed: none reported this month; the emphasis was on stability and artifact integrity. Overall impact: higher production reliability, smoother deployments, and clearer traceability of changes. Technologies/skills demonstrated: Erlang/OTP module loading, binary artifact management, build/release engineering, and repository maintenance.
September 2025
1 Commits • 1 Features
Sep 1, 2025September 2025 — erlang/otp: Delivered a reproducible development environment and build/test automation to accelerate onboarding and improve code quality. Implemented Docker-based environment configurations, editor presets, and build/test scripts to standardize developer workflows and ensure coding standards compliance. Fixed a critical spec issue in EPP:parse_file/2 (PR #10132), addressing potential regressions and improving compilation checks. Impact includes faster feedback loops, more reliable builds, and stronger CI readiness, enabling safer and more efficient contributions to the Erlang/OTP project.
1 Commits • 1 Features
Sep 1, 2025September 2025 — erlang/otp: Delivered a reproducible development environment and build/test automation to accelerate onboarding and improve code quality. Implemented Docker-based environment configurations, editor presets, and build/test scripts to standardize developer workflows and ensure coding standards compliance. Fixed a critical spec issue in EPP:parse_file/2 (PR #10132), addressing potential regressions and improving compilation checks. Impact includes faster feedback loops, more reliable builds, and stronger CI readiness, enabling safer and more efficient contributions to the Erlang/OTP project.
September 2025
July 2025
1 Commits
Jul 1, 2025July 2025 (Monthly summary for erlang/otp): Focused on reliability and correctness of the Beam SSA optimization path. Delivered a bug fix in beam_ssa_opt to fix incorrect block tracking for bsm_shortcut, preserving bs_test_tail instructions when necessary and preventing their unintended removal. This resolves GH-10047. The change was implemented in commit b7f18fb91a196cb288ee1fe5b143589ac1c4d9c8 and included targeted tests to ensure correct preservation across optimization paths. Impact: more stable codegen for BEAM, reduced risk of regression in later optimization passes; alignment with project goals to maintain optimizer correctness with minimal surface area.
July 2025
1 Commits
Jul 1, 2025July 2025 (Monthly summary for erlang/otp): Focused on reliability and correctness of the Beam SSA optimization path. Delivered a bug fix in beam_ssa_opt to fix incorrect block tracking for bsm_shortcut, preserving bs_test_tail instructions when necessary and preventing their unintended removal. This resolves GH-10047. The change was implemented in commit b7f18fb91a196cb288ee1fe5b143589ac1c4d9c8 and included targeted tests to ensure correct preservation across optimization paths. Impact: more stable codegen for BEAM, reduced risk of regression in later optimization passes; alignment with project goals to maintain optimizer correctness with minimal surface area.
April 2025
3 Commits
Apr 1, 2025April 2025 (Month: 2025-04) monthly summary for erlang/otp focusing on reliability, correctness, and maintainable error handling. Implemented targeted runtime fixes and enhanced garbage collection robustness with accompanying test coverage to reduce crash risk and improve predictability across EMU and non-native stacks.
3 Commits
Apr 1, 2025April 2025 (Month: 2025-04) monthly summary for erlang/otp focusing on reliability, correctness, and maintainable error handling. Implemented targeted runtime fixes and enhanced garbage collection robustness with accompanying test coverage to reduce crash risk and improve predictability across EMU and non-native stacks.
April 2025
March 2025
1 Commits
Mar 1, 2025For 2025-03, delivered targeted improvements to the erlang/otp repository focusing on build stability for the ERTS emulator. A compile issue related to DTrace functionality was resolved by including the dtrace-wrapper.h header in bif.c, aided by a focused commit. This work reduces build failures, shortens iteration cycles, and improves CI reliability.
March 2025
1 Commits
Mar 1, 2025For 2025-03, delivered targeted improvements to the erlang/otp repository focusing on build stability for the ERTS emulator. A compile issue related to DTrace functionality was resolved by including the dtrace-wrapper.h header in bif.c, aided by a focused commit. This work reduces build failures, shortens iteration cycles, and improves CI reliability.
February 2025
8 Commits • 3 Features
Feb 1, 2025February 2025: Delivered core VM stability and efficiency improvements in erlang/otp, focusing on memory footprint, safety, and cross-architecture readiness. Implemented hibernate/0 with a refactor of hibernate/3 to shrink memory usage without losing call stacks; disabled unsafe bs_append optimization to prevent race conditions and memory corruption; completed JIT and code-quality refinements (const correctness, enum class usage, NULL-pointer suppression) to boost safety and maintainability; upgraded AsmJit for better instruction encoding, AArch64 calling conventions, and expanded CPU feature detection. These changes reduce operational risk, lower memory pressure under load, and enable more predictable performance across platforms.
8 Commits • 3 Features
Feb 1, 2025February 2025: Delivered core VM stability and efficiency improvements in erlang/otp, focusing on memory footprint, safety, and cross-architecture readiness. Implemented hibernate/0 with a refactor of hibernate/3 to shrink memory usage without losing call stacks; disabled unsafe bs_append optimization to prevent race conditions and memory corruption; completed JIT and code-quality refinements (const correctness, enum class usage, NULL-pointer suppression) to boost safety and maintainability; upgraded AsmJit for better instruction encoding, AArch64 calling conventions, and expanded CPU feature detection. These changes reduce operational risk, lower memory pressure under load, and enable more predictable performance across platforms.
February 2025
January 2025
5 Commits
Jan 1, 2025January 2025: Focused on correctness hardening, static analysis reliability, and test/infra improvements across erlang/otp. Delivered targeted bug fixes with tests, reducing risk of runtime errors and misleading analysis results, and improved license compliance in the test suite. All changes were designed to preserve backward compatibility while increasing observability and developer productivity for the OTP project.
January 2025
5 Commits
Jan 1, 2025January 2025: Focused on correctness hardening, static analysis reliability, and test/infra improvements across erlang/otp. Delivered targeted bug fixes with tests, reducing risk of runtime errors and misleading analysis results, and improved license compliance in the test suite. All changes were designed to preserve backward compatibility while increasing observability and developer productivity for the OTP project.
December 2024
4 Commits • 2 Features
Dec 1, 2024December 2024: Stabilized contract validation, strengthened build-time type handling for _Float16, and improved ARM JIT signature checks in erlang/otp. Delivered targeted fixes and enhancements that reduce crash risk, ensure correct cross-type behavior, and boost portability and runtime reliability across architectures.
4 Commits • 2 Features
Dec 1, 2024December 2024: Stabilized contract validation, strengthened build-time type handling for _Float16, and improved ARM JIT signature checks in erlang/otp. Delivered targeted fixes and enhancements that reduce crash risk, ensure correct cross-type behavior, and boost portability and runtime reliability across architectures.
December 2024
November 2024
3 Commits • 2 Features
Nov 1, 2024November 2024 monthly summary for repository erlang/otp (developer-focused).
November 2024
3 Commits • 2 Features
Nov 1, 2024November 2024 monthly summary for repository erlang/otp (developer-focused).
July 2024
1 Commits • 1 Features
Jul 1, 2024July 2024 monthly summary for repository erlang/otp. Focused on improving build quality and maintainability by introducing compiler-warning suppression macros to reduce noise and clarify unreachable code paths across compilers. Key feature delivered: Suppress misleading compiler warnings in builds, implemented via new macros in erts to suppress bogus warnings, with compiler-aware handling that keeps genuine warnings visible where needed. This change enhances code clarity, reduces unnecessary warnings during compilation, and lowers triage time for build issues. No customer-impact bugs were fixed this month; the work centers on build hygiene and warning management to prevent misdiagnosis of build failures. Overall impact: more reliable builds, faster developer iteration, and clearer code semantics in critical build paths. Technologies/skills demonstrated: C preprocessor macros, cross-compiler conditionals, and maintainability practices within a large Erlang/OTP codebase.
1 Commits • 1 Features
Jul 1, 2024July 2024 monthly summary for repository erlang/otp. Focused on improving build quality and maintainability by introducing compiler-warning suppression macros to reduce noise and clarify unreachable code paths across compilers. Key feature delivered: Suppress misleading compiler warnings in builds, implemented via new macros in erts to suppress bogus warnings, with compiler-aware handling that keeps genuine warnings visible where needed. This change enhances code clarity, reduces unnecessary warnings during compilation, and lowers triage time for build issues. No customer-impact bugs were fixed this month; the work centers on build hygiene and warning management to prevent misdiagnosis of build failures. Overall impact: more reliable builds, faster developer iteration, and clearer code semantics in critical build paths. Technologies/skills demonstrated: C preprocessor macros, cross-compiler conditionals, and maintainability practices within a large Erlang/OTP codebase.
July 2024
June 2024
1 Commits • 1 Features
Jun 1, 2024June 2024 - Monthly summary for erlang/otp. Focused on cross-platform JIT debugging improvements enabling Windows-specific issue reproduction on Linux by forcing the Win32 ABI in the JIT. Implemented changes to calling conventions and runtime call handling to support cross-platform debugging workflows, enhancing cross-platform robustness and debugging efficiency.
June 2024
1 Commits • 1 Features
Jun 1, 2024June 2024 - Monthly summary for erlang/otp. Focused on cross-platform JIT debugging improvements enabling Windows-specific issue reproduction on Linux by forcing the Win32 ABI in the JIT. Implemented changes to calling conventions and runtime call handling to support cross-platform debugging workflows, enhancing cross-platform robustness and debugging efficiency.
Activity
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Quality Metrics
Correctness89.8%
Maintainability87.0%
Architecture85.0%
Performance80.2%
AI Usage21.0%
Skills & Technologies
Programming Languages
AssemblyCC++ErlangJSONMakefilePerlShellYAML
Technical Skills
ARM ArchitectureARM architectureAssembly LanguageBinary AnalysisBuild SystemBuild SystemsC ProgrammingC programmingC++C++ developmentC++ programmingCI/CDCPU ArchitectureCode GenerationCode Refactoring
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline