Benchmarking Skill

Performance benchmarking techniques for Go.

When to Use

Use when measuring or comparing performance.

Writing Benchmarks

func BenchmarkGetUser(b *testing.B) {
    svc := NewService()
    ctx := context.Background()

    b.ResetTimer()
    for i := 0; i < b.N; i++ {
        _, _ = svc.GetUser(ctx, 1)
    }
}

Running Benchmarks

# Run all benchmarks
go test -bench=. -benchmem ./...

# Specific benchmark
go test -bench=BenchmarkGetUser -benchmem

# Multiple runs for accuracy
go test -bench=. -benchmem -count=10

Analyzing Results

BenchmarkGetUser-8    1000000    1250 ns/op    320 B/op    5 allocs/op

• 1000000 - iterations
• 1250 ns/op - time per operation
• 320 B/op - bytes allocated
• 5 allocs/op - allocations per operation

Comparing with benchstat

go test -bench=. -count=10 > old.txt
# make changes
go test -bench=. -count=10 > new.txt
benchstat old.txt new.txt

Best Practices

• Use b.ResetTimer() after setup
• Run multiple times (-count)
• Use benchstat for comparison
• Focus on allocations
• Profile to understand results