paxos问题与相关的资料记下，回头再好好整理
自己思考的几个问题：1. paxos为什么要两阶段？一阶段不行吗？我在paxos made simple中找到这句话【在一次消息中】Several values could be proposed by different proposers at about the same time, leading to a situation in which every acceptor
