if err != nil {
			return nil, err
		}
		fn := filepath.Join(dirPath, "cpu.out")
		f, err := Create(fn)
		if err != nil {
			return nil, err
		}
		err = pprof.StartCPUProfile(f)
		if err != nil {
			return nil, err
		}
		prof.stopFn = func() ([]byte, error) {
			pprof.StopCPUProfile()
			err := f.Close()
			if err != nil {
				return nil, err
			}