code: func (*HandlerT) BlockProfile(file string, nsec uint) error {
  	runtime.SetBlockProfileRate(1)
  	time.Sleep(time.Duration(nsec) * time.Second)
  	defer runtime.SetBlockProfileRate(0)
  	return writeProfile("block", file)
  }
docs: // BlockProfile turns on goroutine profiling for nsec seconds and writes profile data to
  // file. It uses a profile rate of 1 for most accurate information. If a different rate is
  // desired, set the rate and write the profile manually.