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使用 Zookeeper

使用 Akka

创建一个自定义解决方案

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Geode做的最好事情之一是成员管理管理是动态的, 毫无单点故障.  稍微弱的地方是 Locator 服务, 如果所有的 Locators 都有一个急速下降的客户端数, 不能获得服务器的相关信息, 且新的服务器不能添加到集群中, 直到一个Locator再次恢复可用性.  即时 Locators 都宕掉了, 服务器集群仍然是可用的, 客户端仍然能够连接到服务器上.

对于这种情况, 如 Zookeepr 看起来是不满足要求的. 用户必须配置Zookeeper集群, 保证集群是配置好的, 把服务器丢失连接的风险降低到最小. 丢失一个集群的连接将需要一个服务器停机. Zookeeper集群通常情况下比较小, 因此一个 带有200台服务器的Geode 用户将会感觉存在风险, 当使用 一个大的, 7个节点的Zookeeper 集群时.Zookeeper并不响应7~11个节点的需求, 或者提供 UDP 消息通信.

JGroups 已经牵扯和解决了大量的必须在Geode 中 2.2.9 版本上修复的问题. 然而, 为了使用它, 我们 Fork 了一个版本, 修改特定的部分为了满足4, 7, 9 和 10版本.我们 Fork 出特定的部分, 如GMS 和故障检测协议 , 但是视图(View)类需要传递认证的 Credentials.  如果你没有在集群成员关系上使用它, JGroups 仍然在可靠的 UDP 消息传输上是有用的.

Akka 看起来是有前途的, 现在有大量的人使用它.

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For this reason a solution like Zookeeper seems inadequate.  Users would have to configure Zookeeper clusters and make sure the cluster is configured so that servers have minimal risk of losing contact with it.  Losing contact with the cluster would require a server to shut down.  Zookeeper clusters are typically pretty small, so a Geode user with 200 servers might feel at risk when using even a large 7-node Zookeeper cluster.  Zookeeper also doesn't answer requirements 7 through 11 or offer UDP messaging.

JGroups has evolved and solved a lot of problems that had to be fixed in the 2.2.9 copy currently in the Geode repository.  However, in order to use it we would have to fork it and modify certain parts in order to answer requirements 4, 7, 9 and 10.  We could fork only parts, such as GMS and the failure detection protocols but the View class needs to carry Credentials for authentication in order to be useful to Geode.  If not used for cluster membership, JGroups might still be useful for reliable UDP messaging.

Akka looks promising and a lot of people are using it.  

A custom solution that does not leverage other projects for clustering could also be implemented, especially if JGroups is used for reliable UDP messaging.

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