Performance Benchmarks and pprof Profiling

Advanced20 min

Write benchmarks, generate CPU and memory profiles, and analyze performance bottlenecks with pprof.

Prerequisites

-Go 1.21+ installed
-graphviz installed (for pprof visualization)

Steps

Write a benchmark function

Create a benchmark test file following Go naming conventions.

$ cat > handler_bench_test.go << 'EOF' package handler import "testing" func BenchmarkProcess(b *testing.B) { for i := 0; i < b.N; i++ { Process(testData) } } EOF

Run benchmarks

Execute benchmarks with memory allocation statistics.

$ go test -bench=. -benchmem -count=5 ./...

Use -count=5 for statistically meaningful results. Use benchstat to compare multiple runs.

Generate a CPU profile

Run benchmarks and produce a CPU profile for analysis.

$ go test -bench=BenchmarkProcess -cpuprofile=cpu.prof -benchtime=10s ./...

Analyze the CPU profile interactively

Open pprof to explore hotspots in the CPU profile.

$ go tool pprof -http=:6060 cpu.prof

The web UI shows flame graphs, call graphs, and source-level annotations. Focus on the widest bars in the flame graph.

Generate and analyze memory profile

Profile heap allocations to find memory-intensive code paths.

$ go test -bench=BenchmarkProcess -memprofile=mem.prof ./... && go tool pprof -http=:6060 mem.prof

Memory profiles show allocations, not current memory usage. Look for high alloc_objects to find GC pressure.

Compare benchmarks with benchstat

Use benchstat to compare two benchmark runs and detect regressions.

$ go test -bench=. -count=10 ./... > old.txt && go test -bench=. -count=10 ./... > new.txt && benchstat old.txt new.txt

Install benchstat with: go install golang.org/x/perf/cmd/benchstat@latest

Full Script

full-script.sh

#!/bin/bash
# Go Benchmark and Profiling Workflow
set -euo pipefail

PACKAGE=${1:-"./..."}

echo "=== Running Benchmarks ==="
go test -bench=. -benchmem -count=3 "$PACKAGE" | tee bench.txt

echo ""
echo "=== Generating CPU Profile ==="
go test -bench=. -cpuprofile=cpu.prof -benchtime=5s "$PACKAGE"

echo ""
echo "=== Generating Memory Profile ==="
go test -bench=. -memprofile=mem.prof "$PACKAGE"

echo ""
echo "=== Top CPU Consumers ==="
go tool pprof -top cpu.prof 2>/dev/null | head -20

echo ""
echo "=== Top Memory Allocators ==="
go tool pprof -top mem.prof 2>/dev/null | head -20

echo ""
echo "=== Profiling Commands ==="
echo "Interactive CPU:  go tool pprof -http=:6060 cpu.prof"
echo "Interactive Mem:  go tool pprof -http=:6060 mem.prof"
echo "Compare runs:     benchstat old.txt new.txt"
echo "Trace:            go test -trace=trace.out && go tool trace trace.out"

FAQ

Discussion

Loading comments...

#!/bin/bash # Go Benchmark and Profiling Workflow set -euo pipefail PACKAGE=${1:-"./..."} echo "=== Running Benchmarks ===" go test -bench=. -benchmem -count=3 "$PACKAGE" | tee bench.txt echo "" echo "=== Generating CPU Profile ===" go test -bench=. -cpuprofile=cpu.prof -benchtime=5s "$PACKAGE" echo "" echo "=== Generating Memory Profile ===" go test -bench=. -memprofile=mem.prof "$PACKAGE" echo "" echo "=== Top CPU Consumers ===" go tool pprof -top cpu.prof 2>/dev/null | head -20 echo "" echo "=== Top Memory Allocators ===" go tool pprof -top mem.prof 2>/dev/null | head -20 echo "" echo "=== Profiling Commands ===" echo "Interactive CPU: go tool pprof -http=:6060 cpu.prof" echo "Interactive Mem: go tool pprof -http=:6060 mem.prof" echo "Compare runs: benchstat old.txt new.txt" echo "Trace: go test -trace=trace.out && go tool trace trace.out"