Benchmarking, Profiling, Tracing

• Benchmarking - focus on a particular piece of code, allowing measurement of time and/or memory information.

• Profiling - aggregated data collected through sampling during program (or test) execution. Profiling has no timeline.

• Tracing - data collected through events occurring during program (or test) execution. They give a chronological view of program's execution with detailed information about heap, GC, goroutines, core usage, ...

Running benchmarks

Run tests:

• with benchmarks (time) : go test ./fibonacci -bench .

• with benchmarks (time and memory) : go test ./fibonacci -bench . -benchmem

Profiling benchmarks

Get profiling data from the benchmarks:

• CPU profiling using -cpuprofile=cpu.out

• Memory profiling using -benchmem -memprofile=mem.out

go test ./fibonacci \
  -bench BenchmarkSuite \
  -benchmem \
  -cpuprofile=cpu.out \
  -memprofile=mem.out

Viewing profiling data

• through command line : go tool pprof cpu.out

• with a browser : go tool pprof -http=localhost:8080 cpu.out

Tracing

go test ./fibonacci \
  -bench BenchmarkSuite \
  -trace=trace.out

go tool trace trace.out

Getting Memory Statistics

• runtime.ReadMemStats allows you to retrieve memory statistics for the current Go process.

package main

import (
	"fmt"
	"runtime"
)

func main() {
	var memStats runtime.MemStats

	runtime.ReadMemStats(&memStats)

	fmt.Printf("Total allocated memory (in bytes): %d\n", memStats.Alloc)
	fmt.Printf("Heap memory (in bytes): %d\n", memStats.HeapAlloc)
	fmt.Printf("Number of garbage collections: %d\n", memStats.NumGC)
}

Packages:

• Go testing package : https://golang.org/pkg/testing/

• Go runtime package : https://golang.org/pkg/runtime/

• Go trace package : https://golang.org/pkg/runtime/trace/

• Go pprof package : https://golang.org/pkg/runtime/pprof/

Resources:

• Uber Talk on Profiling and Optimizing Go