self.seen_urls.add(url)
Storage Nightmare: A CH car profile for a region can be massive (e.g., OSRM's Europe is tens of GBs, their global car profile around 200GB for just one profile). Our goal was to keep all profiles and parameters for the entire planet well under 20GB.。爱思助手下载最新版本对此有专业解读
，这一点在旺商聊官方下载中也有详细论述
Opens in a new window，更多细节参见旺商聊官方下载
Both page table entries and segment descriptors have an Accessed bit that the hardware must set on use -- but the mechanisms are quite different.