import (
	. "context"
	"fmt"
	"runtime"
	"sync"
	"testing"
	"time"
)

func BenchmarkCommonParentCancel(b *testing.B) {
	root := WithValue(Background(), "key", "value")
	shared, sharedcancel := WithCancel(root)
	defer sharedcancel()

	b.ResetTimer()
	b.RunParallel(func(pb *testing.PB) {
		x := 0
		for pb.Next() {
			ctx, cancel := WithCancel(shared)
			if ctx.Value("key").(string) != "value" {