Benchmark Analysis

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

# Save baseline
go test -bench=. -benchmem -count=10 > old.txt

# Make changes, save new results
go test -bench=. -benchmem -count=10 > new.txt

# Compare
benchstat old.txt new.txt

# Output:
# name     old time/op    new time/op    delta
# Parse-8    1.23µs ± 2%    0.98µs ± 1%  -20.33%  (p=0.000 n=10+10)
# Marshal-8  2.45µs ± 3%    2.41µs ± 2%     ~     (p=0.142 n=10+10)

# Filter by name
benchstat -filter 'Parse' old.txt new.txt

# Compare specific benchmarks
benchstat -col old old.txt new.txt

# HTML report
benchstat -html old.txt new.txt > report.html

# Run many iterations for stability
go test -bench=. -benchmem -count=20

# Pin CPU frequency (Linux)
sudo cpupower frequency-set -g performance

# Disable turbo boost
echo 1 | sudo tee /sys/devices/system/cpu/intel_pstate/no_turbo

# Close other applications
# Stop unnecessary services
# Use a dedicated benchmark machine

# Use benchstat's statistical analysis
benchstat -count 10 old.txt new.txt

# Check for outliers
go test -bench=. -benchmem -count=50 | sort -k3 -n

name: Benchmark
on:
  pull_request:
    paths: ['**/*.go']

jobs:
  benchmark:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - uses: actions/setup-go@v5
        with:
          go-version: "1.22"

      - name: Save baseline
        run: |
          git checkout main
          go test -bench=. -benchmem -count=5 -timeout=10m > old.txt

      - name: Save PR results
        run: |
          git checkout -
          go test -bench=. -benchmem -count=5 -timeout=10m > new.txt

      - name: Compare
        run: |
          go install golang.org/x/perf/cmd/benchstat@latest
          benchstat old.txt new.txt

      - name: Comment on PR
        uses: actions/github-script@v7
        with:
          script: |
            const output = require('child_process')
              .execSync('benchstat old.txt new.txt')
              .toString();
            github.rest.issues.createComment({
              issue_number: context.issue.number,
              body: `## Benchmark Results\n\n${output}`
            });