yarn狀態機可視化

YARN中實現了多個狀態機對象，包括ResourceManager中的RMAppImpl、RMApp-AttemptImpl、RMContainerImpl和RMNodeImpl，NodeManager中的ApplicationImpl、ContainerImpl和LocalizedResource，MRAppMaster中的JobImpl、TaskImpl和TaskAttemptImpl等。爲了便於用戶查看這些狀態機的狀態變化以及相關事件，YARN提供了一個狀態機可視化工具，具體操作步驟如下。

步驟1　將狀態機轉化爲graphviz(.gv)格式的文件，在源代碼根目錄下執行編譯命令如下：

mvn compile -Pvisualize

經過該步驟後，本地目錄中生成了ResourceManager.gv、NodeManager.gv和MapReduce.gv三個graphviz格式的文件。NodeManager.gv文件中LocalizedResource狀態機部分內容如下：

subgraph cluster_LocalizedResource {
label="LocalizedResource"
  "LocalizedResource.FAILED" [ label = FAILED ];
  "LocalizedResource.DOWNLOADING" [ label = DOWNLOADING ];
  "LocalizedResource.DOWNLOADING" -> "LocalizedResource.DOWNLOADING" [ label = "REQUEST,\nRELEASE" ];
  "LocalizedResource.DOWNLOADING" -> "LocalizedResource.FAILED" [ label = "LOCALIZATION_FAILED" ];
  "LocalizedResource.DOWNLOADING" -> "LocalizedResource.LOCALIZED" [ label = "LOCALIZED" ];
  "LocalizedResource.INIT" [ label = INIT ];
  "LocalizedResource.INIT" -> "LocalizedResource.DOWNLOADING" [ label = "REQUEST" ];
  "LocalizedResource.LOCALIZED" [ label = LOCALIZED ];
  "LocalizedResource.LOCALIZED" -> "LocalizedResource.LOCALIZED" [ label = "REQUEST,\nRELEASE" ];
}

步驟2　使用可視化包graphviz中的相關命令生成狀態機圖，Shell命令具體如下：

dot -Tpng NodeManager.gv > NodeManager.png

如果尚未安裝graphviz包，操作該步驟之前先要安裝該包，cent os安裝命令如下：

sudo yum install graphviz

打開NodeManager.png，如下圖所示(爲了便於展示，分拆成了兩個圖)：