code: func (req *Request) ReleaseBody(size int) {
  	if cap(req.body.B) > size {
  		req.closeBodyStream()
  		req.body = nil
  	}
  }
docs: // ReleaseBody retires the request body if it is greater than "size" bytes.
  //
  // This permits GC to reclaim the large buffer.  If used, must be before
  // ReleaseRequest.
  //
  // Use this method only if you really understand how it works.
  // The majority of workloads don't need this method.