【Golang】runtimeを調べてみた

Go言語のruntimeはOSやプロセスの情報を得ることができます。
runtime - The Go Programming Language

CPU情報はDeprecatedになってしまったようですね。

下記のサンプルコードをもとにちょっと自分でも書いてみました。
golangcode.com

package main

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

func main() {
        fmt.Println("--- Params ---")
        fmt.Printf("GOROOT = %v\n",runtime.GOROOT())
        fmt.Printf("NumCPU = %v\n",  runtime.NumCPU())
        fmt.Printf("NumGoroutine = %v\n",  runtime.NumGoroutine())

        fmt.Println("--- memory test ---")
        fmt.Println("--- before ---")
        PrintMemUsage()
        fmt.Println("--- start ---")
        var mem_alloc [][]int
        for i := 0 ; i < 4 ; i++ {
                a := make([]int, 0, 999999)
                mem_alloc = append(mem_alloc, a)

                PrintMemUsage()
                time.Sleep(time.Second)
        }
        PrintMemUsage()
        fmt.Println("--- After GC ---")
        runtime.GC()
        PrintMemUsage()

}

func PrintMemUsage() {
        var m runtime.MemStats
        runtime.ReadMemStats(&m)

        fmt.Printf("Alloc = %v MiB\t", bToMb(m.Alloc))
        fmt.Printf("TotalAlloc = %v MiB\t", bToMb(m.TotalAlloc))
        fmt.Printf("Sys = %v MiB\t", bToMb(m.Sys))
        fmt.Printf("Mallocs = %v MiB\t", bToMb(m.Mallocs))
        fmt.Printf("Frees = %v MiB\t", bToMb(m.Frees))
        fmt.Printf("HeapAlloc = %v MiB\t", bToMb(m.HeapAlloc))
        fmt.Printf("HeapSys = %v MiB\t", bToMb(m.HeapSys))
        fmt.Printf("NumGC = %v", m.NumGC)
        fmt.Printf("\n")
}

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

こんな結果が取れます。

--- Params ---
GOROOT = /opt/go
NumCPU = 1
NumGoroutine = 1
--- memory test ---
--- before ---
Alloc = 0 MiB   TotalAlloc = 0 MiB      Sys = 1 MiB     Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 0 MiB       HeapSys = 0 MiB NumGC = 0
--- start ---
Alloc = 7 MiB   TotalAlloc = 7 MiB      Sys = 11 MiB    Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 7 MiB       HeapSys = 8 MiB NumGC = 1
Alloc = 15 MiB  TotalAlloc = 15 MiB     Sys = 19 MiB    Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 15 MiB      HeapSys = 16 MiB        NumGC = 2
Alloc = 22 MiB  TotalAlloc = 22 MiB     Sys = 26 MiB    Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 22 MiB      HeapSys = 23 MiB        NumGC = 3
Alloc = 30 MiB  TotalAlloc = 30 MiB     Sys = 34 MiB    Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 30 MiB      HeapSys = 31 MiB        NumGC = 4
Alloc = 30 MiB  TotalAlloc = 30 MiB     Sys = 34 MiB    Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 30 MiB      HeapSys = 31 MiB        NumGC = 4
--- After GC ---
Alloc = 0 MiB   TotalAlloc = 30 MiB     Sys = 34 MiB    Mallocs = 0 MiB Frees = 0 MiB   HeapAlloc = 0 MiB       HeapSys = 31 MiB        NumGC = 5