YARN 中的 Application Manager 和 Application Master 之间的区别? [英] Difference between Application Manager and Application Master in YARN?
问题描述
我了解了 MRv1 的工作原理.现在我正在尝试了解 MRv2.. YARN 中的 Application Manager 和 Application Master 有什么区别?
I understood how MRv1 works.Now I am trying to understand MRv2.. what's the difference between Application Manager and Application Master in YARN?
推荐答案
Application Master 和 Application Manager 这两个术语经常互换使用.实际上，Application Master 是请求、启动和监控应用程序特定资源的主要容器，而 Application Manager 是 ResourceManager 中的一个组件.下面给出了有关应用程序管理器的更多详细信息.
The terms Application Master and Application Manager are often used interchangeably. In reality Application Master is the main container requesting, launching and monitoring application specific resources, whereas Application Manager is a component inside ResourceManager. More details about Application Manager is given below.
ApplicationsManager 负责维护提交的集合应用程序.申请提交后，首先验证申请的规范并拒绝任何为其请求无法满足的资源的应用程序ApplicationMaster(即集群中没有节点拥有足够的资源运行 ApplicationMaster 本身).然后它确保没有其他应用程序已经使用相同的应用程序 ID 提交 - 可能由错误导致的场景或恶意客户端.最后，它将被允许的应用程序转发给调度程序.该组件还负责记录和管理完成的应用程序在它们完全从 ResourceManager 中撤出之前的一段时间记忆.当应用程序完成时，它会在守护进程的日志文件.最后，ApplicationsManager 会在很久之后保留已完成应用程序的缓存应用程序完成以支持用户对应用程序数据的请求(通过 Web UI 或命令线).配置属性 yarn.resourcemanager.max-completed-applications控制 ResourceManager 的此类已完成应用程序的最大数量记得在任何时间点.缓存是一个先进先出的列表，包含最旧的应用程序正在搬出以容纳新完成的应用程序.
The ApplicationsManager is responsible for maintaining a collection of submitted applications. After application submission, it first validates the application’s specifications and rejects any application that requests unsatisfiable resources for its ApplicationMaster (i.e., there is no node in the cluster that has enough resources to run the ApplicationMaster itself). It then ensures that no other application was already submitted with the same application ID—a scenario that can be caused by an erroneous or a malicious client. Finally, it forwards the admitted application to the scheduler. This component is also responsible for recording and managing finished applications for a while before they are completely evacuated from the ResourceManager’s memory. When an application finishes, it places an ApplicationSummary in the daemon’s log file. Finally, the ApplicationsManager keeps a cache of completed applications long after applications finish to support users’ requests for application data (via web UI or command line). The configuration property yarn.resourcemanager.max-completed-applications controls the maximum number of such finished applications that the ResourceManager remembers at any point of time. The cache is a first-in, first-out list, with the oldest applications being moved out to accommodate freshly finished applications.
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