Profiling pages (debug build only) To optimize this software more, I need profilier to see which part is taking a time.

Changes

6 changed files (+65/-0)

• .gitignore
  • @@ -7,3 +7,6 @@ demo/*
    # QEMU disk image. *.qcow2 + + # Downloaded profile generated by net/http/pprof. + profile
• DEVELOPMENT.md
  • @@ -21,6 +21,20 @@ Run `nix run .#testing` (you need Nix Flakes) or follow steps described in `test
    Once the test server is ready, pass your desired test file to `k6 run` command. Nix user can use `nix run .#k6 -- run` without installing k6 manually. + ## Profiling + + Add `debug` build tag then access `/debug/pprof/` for profiling. + The profiling feature uses [runtime/pprof](https://pkg.go.dev/runtime/pprof) in Go Standard library. + + ### Example Usage + + 1. Launch the server using `go run . -tags debug . --config ./demo/config.yaml` + 2. Start profiling for 10s using `curl -sL http://localhost:5555/debug/pprof/profile?seconds=10 > profile` + 3. Access a page / pages you want to profile + 4. Wait for the download command (`curl`) to finish + 5. Launch profiling viewer using `go tool pprof -http localhost:8082 profile` + 6. Access http://localhost:8082 + ## Code Formatting This project use [dprint](https://dprint.dev/).
• flake.nix
  • @@ -85,6 +85,8 @@
    packages = with pkgs; [ go delve + # pprof requires Graphviz for generating visualizations. + graphviz ]; };
• routes/debug/debug.go (new)
  • @@ -0,0 +1,25 @@
    + //go:build debug + + // Copyright 2026 Shota FUJI <pockawoooh@gmail.com> + // SPDX-License-Identifier: MIT + // + // Debug routes. To access this routes, add a "debug" build tag. + + package debug + + import ( + "net/http" + "net/http/pprof" + ) + + func Register(mux *http.ServeMux) { + // We have to use "/debug/pprof" path as the "net/http/pprof" package + // recklessly hardcodes the path. That problematic package also registers + // these paths using problematic "init()" calls, but our handlers takes + // higher precedences, so we have to register manually. + mux.HandleFunc("GET /debug/pprof/", pprof.Index) + mux.HandleFunc("GET /debug/pprof/cmdline", pprof.Cmdline) + mux.HandleFunc("GET /debug/pprof/profile", pprof.Profile) + mux.HandleFunc("GET /debug/pprof/symbol", pprof.Symbol) + mux.HandleFunc("GET /debug/pprof/trace", pprof.Trace) + }
• routes/debug/stub.go (new)
  • @@ -0,0 +1,18 @@
    + //go:build !debug + + // Copyright 2026 Shota FUJI <pockawoooh@gmail.com> + // SPDX-License-Identifier: MIT + // + // This file will be used for non-debug build, to provide no-op handler. + // The purpose of this conditional compilation is to prevent pprof code from + // being included in the non-debug builds. The "net/http/pprof" package uses + // "init" to register default routes carelessly and not importing the file + // is simple and reliable solution. + + package debug + + import ( + "net/http" + ) + + func Register(*http.ServeMux) {}
• routes/handler.go
  • @@ -8,6 +8,7 @@ import (
    "github.com/microcosm-cc/bluemonday" "github.com/pocka/legit/config" "github.com/pocka/legit/renderer/html" + "github.com/pocka/legit/routes/debug" ) // Checks for gitprotocol-http(5) specific smells; if found, passes
  • @@ -54,6 +55,8 @@ func Handlers(c *config.Config, staticDir fs.FS, templatesDir fs.FS) *http.Serve
    d.t = template.Must(template.ParseFS(d.templatesDir, "*")) } + debug.Register(mux) + mux.HandleFunc("GET /", d.Index) mux.HandleFunc("GET /static/{file}", d.ServeStatic) mux.HandleFunc("GET /{name}", d.Multiplex)