# 为什么需要分布式系统

## 分布式系统是什么

A distributed system is a system whose components are located on different networked computers, which communicate and coordinate their actions by passing messages to one another.[1] The components interact with one another in order to achieve a common goal. Three significant characteristics of distributed systems are: concurrency of components, lack of a global clock, and independent failure of components.[1] Examples of distributed systems vary from SOA-based systems to massively multiplayer online games to peer-to-peer applications.


### 分布式系统遇到的问题

• 系统的吞吐量会变大，但是响应时间会变长。
• 某个非核心服务出现故障，为了不影响主流程，要加入服务降级和熔断策略
• 同一个请求可能被服务集群里面的多台机器处理，然后保证幂等性