feat(prefork): add support for process monitoring and callbacks in prefork mode by ReneWerner87 · Pull Request #4037 · gofiber/fiber

ReneWerner87 · 2026-01-28T08:06:37Z

Modified fasthttp version
ReneWerner87/fasthttp@master...ReneWerner87:fasthttp:prefork_optimization
PR to fasthttp is coming

coderabbitai · 2026-01-28T08:06:51Z

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gemini-code-assist · 2026-01-28T08:06:59Z

Summary of Changes

Hello @ReneWerner87, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly refactors Fiber's prefork implementation by integrating the fasthttp/prefork package. This change introduces robust process monitoring capabilities, including automatic child process recovery, and extends prefork support to custom listeners via a new callback mechanism. The goal is to provide a more stable and flexible prefork experience for Fiber applications.

Highlights

Integration with fasthttp/prefork: Fiber's internal prefork implementation has been replaced by the more robust fasthttp/prefork package, centralizing prefork logic and leveraging its features.
Child Process Monitoring and Recovery: The prefork mode now includes built-in monitoring for child process crashes and automatic recovery, configurable via a new PreforkRecoverThreshold in ListenConfig.
Enhanced Custom Listener Support: The app.Listener() method now fully supports prefork mode through a new OnPreforkServe callback, allowing each child process to create its own reuseport listener, removing a previous limitation.

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Code Review

This pull request refactors the prefork implementation to leverage fasthttp's native capabilities, introducing OnPreforkServe for custom listeners and PreforkRecoverThreshold for process monitoring. While these are valuable additions, a critical supply chain vulnerability has been identified: the go.mod file replaces a core dependency with a personal fork using a suspicious, future-dated pseudo-version. This practice should be remediated by using official, verified dependencies. Furthermore, there is a critical issue with a missing type definition that will prevent compilation, and an opportunity to refactor duplicated code to enhance maintainability.

prefork.go

go.mod

prefork.go

codecov · 2026-02-06T08:42:28Z

Codecov Report

❌ Patch coverage is 92.85714% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.27%. Comparing base (6c19f48) to head (3fe1c7d).

Files with missing lines	Patch %	Lines
prefork.go	92.50%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4037      +/-   ##
==========================================
+ Coverage   91.16%   91.27%   +0.10%     
==========================================
  Files         123      124       +1     
  Lines       11855    11841      -14     
==========================================
  Hits        10808    10808              
+ Misses        659      648      -11     
+ Partials      388      385       -3

Flag	Coverage Δ
unittests	`91.27% <92.85%> (+0.10%)`	⬆️

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…tion Replace Fiber's own prefork implementation with fasthttp's prefork package. This eliminates duplicated process management logic and adds new features: - IsChild() now delegates to prefork.IsChild() - Master process uses fasthttp's recovery loop (RecoverThreshold) - Callbacks (OnChildSpawn, OnMasterReady, OnChildRecover) integrate Fiber's hooks system (OnFork, OnListen, startup message) - CommandProducer enables clean test injection (replaces testPreforkMaster) - OnMasterDeath replaces Fiber's watchMaster (now in fasthttp) - New PreforkRecoverThreshold field in ListenConfig - prefork_logger.go adapts Fiber's logger to fasthttp's Logger interface - go.mod uses replace directive for local fasthttp development Code reduction: ~200 lines of process management removed from Fiber. All existing tests adapted for recovery behavior (ErrOverRecovery). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Ensures deterministic and fast execution regardless of GOMAXPROCS count. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Use github.com/ReneWerner87/fasthttp@2802b1a (prefork_optimization branch) instead of local ../fasthttp path, so CI and other developers can resolve the dependency. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Includes fix for ListenAndServeTLS parameter order preservation. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- prefork_logger.go: use grouped import declaration - prefork.go: rename unused 'files' parameter to '_' - prefork.go: wrap external errors from cmd.Start() and ListenAndServe() Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gaby

Few questions, over all this makes fiber prefork more simple and moves a lot of the boilerplate to fasthttp which is great.

prefork.go

- Move windowsOS constant to constants.go (global consts file) - Make prefork logger configurable via ListenConfig.PreforkLogger - Define PreforkLoggerInterface for custom logger implementations - Use logger.Printf instead of direct log.Warnf in OnChildRecover - Remove unused log import from prefork.go Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ReneWerner87 · 2026-04-11T19:33:44Z

replaced by #4210

ReneWerner87 added v3 ✏️ Feature 🤖 Dependencies labels Jan 28, 2026

ReneWerner87 removed the 🤖 Dependencies label Jan 28, 2026

ReneWerner87 added this to v3 Jan 28, 2026

ReneWerner87 added this to the v3 milestone Jan 28, 2026

ReneWerner87 added the 🤖 Dependencies label Jan 28, 2026

ReneWerner87 mentioned this pull request Jan 28, 2026

feat: enhance prefork functionality with new configuration options and improved child process recovery #4032

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gemini-code-assist bot reviewed Jan 28, 2026

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ReneWerner87 modified the milestones: v3.0.0, v3 Feb 1, 2026

ReneWerner87 force-pushed the prefork_optimization branch from d383b0c to 67a27e7 Compare April 11, 2026 18:09

ReneWerner87 and others added 3 commits April 11, 2026 20:09

test(prefork): add PreforkRecoverThreshold to invalid-command test case

dba20e1

Ensures deterministic and fast execution regardless of GOMAXPROCS count. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

refactor(prefork): use windowsOS constant in dummyCmd for consistency

cfc5a9d

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ReneWerner87 force-pushed the prefork_optimization branch from 67a27e7 to cfc5a9d Compare April 11, 2026 18:10

ReneWerner87 and others added 3 commits April 11, 2026 20:17

build: update fasthttp fork reference to c1055ce

3124fc2

Includes fix for ListenAndServeTLS parameter order preservation. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gaby reviewed Apr 11, 2026

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ReneWerner87 merged commit 3fe1c7d into main Apr 11, 2026
16 of 17 checks passed

ReneWerner87 deleted the prefork_optimization branch April 11, 2026 19:29

github-project-automation bot moved this to Done in v3 Apr 11, 2026

ReneWerner87 restored the prefork_optimization branch April 11, 2026 19:31

ReneWerner87 mentioned this pull request Apr 11, 2026

feat(prefork): delegate to fasthttp/prefork to eliminate code duplication #4210

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feat(prefork): add support for process monitoring and callbacks in prefork mode#4037

feat(prefork): add support for process monitoring and callbacks in prefork mode#4037
ReneWerner87 merged 7 commits intomainfrom
prefork_optimization

ReneWerner87 commented Jan 28, 2026

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