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