using uber automaxprocs to set GOMAXPROCS correctly in container context

ctr_set_maxprocs.go

package main

import (
	"fmt"
	"runtime"

	"go.uber.org/automaxprocs/maxprocs"
)

func main() {
	fmt.Printf("direct runtime.NumCPU: %d\n", runtime.NumCPU())
	fmt.Printf("direct runtime.GOMAXPROCS(0): %d\n", runtime.GOMAXPROCS(0))
	maxprocs.Set(maxprocs.Logger(func(s string, i ...interface{}) {
		fmt.Printf(s, i...)
		fmt.Println()
	}))
	fmt.Printf("after uber maxprocs.Set, runtime.NumCPU: %d\n", runtime.NumCPU())
	fmt.Printf("after uber maxprocs.Set, runtime.GOMAXPROCS(0): %d\n", runtime.GOMAXPROCS(0))
}

// # docker run --rm --cpus 2 zengxu/goctrlimit
// direct runtime.NumCPU: 8
// direct runtime.GOMAXPROCS(0): 8
// maxprocs: Updating GOMAXPROCS=2: determined from CPU quota
// after uber maxprocs.Set, runtime.NumCPU: 8
// after uber maxprocs.Set, runtime.GOMAXPROCS(0): 2