pprof Reference

Enable pprof HTTP Server

Pprof endpoints MUST be protected with basic auth — NEVER expose them publicly. They leak sensitive runtime information (goroutine stacks, memory contents) and can be abused to DoS your service (CPU profiling is expensive). Pprof SHOULD be toggled via a PPROF_ENABLED environment variable.

Quick Setup (Development)

import _ "net/http/pprof"

func main() {
    go func() {
        log.Println(http.ListenAndServe("localhost:6060", nil))
    }()
    // ... rest of app
}

Secure Setup (Production)

For production, protect endpoints with basic auth:

import "net/http/pprof"

func setupPprof(mux *http.ServeMux) {
    if os.Getenv("PPROF_ENABLED") != "true" {
        return
    }

    // Protect pprof endpoints with basic auth — never expose unauthenticated
    username := os.Getenv("PPROF_USERNAME")
    password := os.Getenv("PPROF_PASSWORD")
    if username == "" || password == "" {
        panic("PPROF_USERNAME and PPROF_PASSWORD must be set when pprof is enabled")
    }
    auth := basicAuth(username, password)

    mux.Handle("/debug/pprof/", auth(http.HandlerFunc(pprof.Index)))
    mux.Handle("/debug/pprof/cmdline", auth(http.HandlerFunc(pprof.Cmdline)))
    mux.Handle("/debug/pprof/profile", auth(http.HandlerFunc(pprof.Profile)))
    mux.Handle("/debug/pprof/symbol", auth(http.HandlerFunc(pprof.Symbol)))
    mux.Handle("/debug/pprof/trace", auth(http.HandlerFunc(pprof.Trace)))

    slog.Info("pprof endpoints enabled (basic auth required)")
}

// basicAuth wraps an http.Handler with HTTP Basic Authentication.
func basicAuth(username, password string) func(http.Handler) http.Handler {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            u, p, ok := r.BasicAuth()
            if !ok || u != username || subtle.ConstantTimeCompare([]byte(p), []byte(password)) != 1 {
                w.Header().Set("WWW-Authenticate", `Basic realm="pprof"`)
                http.Error(w, "unauthorized", http.StatusUnauthorized)
                return
            }
            next.ServeHTTP(w, r)
        })
    }
}

Profile Types

Profile	Command	What It Shows
CPU	`go tool pprof profile`	Where CPU time is spent
Heap	`go tool pprof heap`	Memory allocations, live objects
Goroutine	`go tool pprof goroutine`	Stack traces of all goroutines
Block	`go tool pprof block`	Blocking operations (needs SetBlockProfileRate)
Mutex	`go tool pprof mutex`	Lock contention (needs SetMutexProfileFraction)
Alloc	`go tool pprof -alloc_space heap`	Cumulative allocations (not current heap)

Capturing Profiles

# CPU profiles SHOULD capture at least 30 seconds for meaningful data (30s default).
# Ensure your HTTP server's request timeout exceeds the capture duration.
curl http://localhost:6060/debug/pprof/profile?seconds=30 > cpu.prof

# Heap snapshot
curl http://localhost:6060/debug/pprof/heap > heap.prof

# Goroutine dump (human-readable)
curl http://localhost:6060/debug/pprof/goroutine?debug=2 > goroutines.txt

# Goroutine profile (for pprof analysis)
curl http://localhost:6060/debug/pprof/goroutine > goroutine.prof

# Go 1.26 experimental goroutine leak profile, only with GOEXPERIMENT=goroutineleakprofile
curl http://localhost:6060/debug/pprof/goroutineleak?debug=2
go tool pprof http://localhost:6060/debug/pprof/goroutineleak

# Mutex contention
curl http://localhost:6060/debug/pprof/mutex > mutex.prof

# Block profile
curl http://localhost:6060/debug/pprof/block > block.prof

Analyzing and Interpreting Profiles

→ See samber/cc-skills-golang@golang-benchmark skill (pprof.md) for interpreting profiles: top, list, peek, common profile patterns (flat vs cum, GC churn, memory leaks), and compiler diagnostics. See also compiler-analysis.md for escape analysis and inlining decisions.

Quick start:

go tool pprof cpu.prof          # interactive analysis
go tool pprof -http=:8080 cpu.prof  # graphical flamegraph
go tool pprof -base heap1.prof heap2.prof  # compare heap snapshots

Remote Profiling (Production)

For production servers, replace localhost:6060 with your server address and use basic auth credentials.

Safety: idle pprof endpoints have low overhead, but profile captures are not free. CPU profiling samples for the requested duration, heap profiles may trigger extra work, and block/mutex profiles add runtime overhead when enabled.

→ See samber/cc-skills-golang@golang-observability skill for continuous profiling with Pyroscope. → See samber/cc-skills-golang@golang-benchmark skill for investigation session setup and Prometheus-based performance tracking.

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