zhihai xu created YARN-4095: ------------------------------- Summary: Avoid sharing AllocatorPerContext object in LocalDirAllocator between ShuffleHandler and LocalDirsHandlerService. Key: YARN-4095 URL: https://issues.apache.org/jira/browse/YARN-4095 Project: Hadoop YARN Issue Type: Improvement Components: nodemanager Reporter: zhihai xu Assignee: zhihai xu
Currently {{ShuffleHandler}} and {{LocalDirsHandlerService}} share {{AllocatorPerContext}} object in {{LocalDirAllocator}} for configuration {{NM_LOCAL_DIRS}} because {{AllocatorPerContext}}s are stored in a static TreeMap with configuration name as key {code} private static Map <String, AllocatorPerContext> contexts = new TreeMap<String, AllocatorPerContext>(); {code} {{LocalDirsHandlerService}} and {{ShuffleHandler}} both create a {{LocalDirAllocator}} using {{NM_LOCAL_DIRS}}. Even they don't use the same {{Configuration}} object, but they will use the same {{AllocatorPerContext}} object. Also {{LocalDirsHandlerService}} may change {{NM_LOCAL_DIRS}} value in its {{Configuration}} object to exclude full and bad local dirs, {{ShuffleHandler}} always uses the original {{NM_LOCAL_DIRS}} value in its {{Configuration}} object. So every time {{AllocatorPerContext#confChanged}} is called by {{ShuffleHandler}} after {{LocalDirsHandlerService}}, {{AllocatorPerContext}} need be reinitialized because {{NM_LOCAL_DIRS}} value is changed. This will cause some overhead. {code} String newLocalDirs = conf.get(contextCfgItemName); if (!newLocalDirs.equals(savedLocalDirs)) { {code} So it will be a good improvement to not share the same {{AllocatorPerContext}} instance between {{ShuffleHandler}} and {{LocalDirsHandlerService}}. -- This message was sent by Atlassian JIRA (v6.3.4#6332)