Go print current memory

print-memory.go

package main

import (
    "runtime"
    "fmt"
    "time"
)

func main() {
    // Print our starting memory usage (should be around 0mb)
    PrintMemUsage()

    var overall [][]int
    for i := 0; i<4; i++ {

        // Allocate memory using make() and append to overall (so it doesn't get 
        // garbage collected). This is to create an ever increasing memory usage 
        // which we can track. We're just using []int as an example.
        a := make([]int, 0, 999999)
        overall = append(overall, a)

        // Print our memory usage at each interval
        PrintMemUsage()
        time.Sleep(time.Second)
    }

    // Clear our memory and print usage, unless the GC has run 'Alloc' will remain the same
    overall = nil
    PrintMemUsage()

    // Force GC to clear up, should see a memory drop
    runtime.GC()
    PrintMemUsage()
}

// PrintMemUsage outputs the current, total and OS memory being used. As well as the number 
// of garage collection cycles completed.
func PrintMemUsage() {
        var m runtime.MemStats
        runtime.ReadMemStats(&m)
        // For info on each, see: https://golang.org/pkg/runtime/#MemStats
        fmt.Printf("Alloc = %v MiB", bToMb(m.Alloc))
        fmt.Printf("\tTotalAlloc = %v MiB", bToMb(m.TotalAlloc))
        fmt.Printf("\tSys = %v MiB", bToMb(m.Sys))
        fmt.Printf("\tNumGC = %v\n", m.NumGC)
}

func bToMb(b uint64) uint64 {
    return b / 1024 / 1024
}