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Jason Lowe commented on YARN-4095: ---------------------------------- +1 lgtm. Committing this. > 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 > Attachments: YARN-4095.000.patch, YARN-4095.001.patch > > > Currently {{ShuffleHandler}} and {{LocalDirsHandlerService}} share > {{AllocatorPerContext}} object in {{LocalDirAllocator}} for configuration > {{NM_LOCAL_DIRS}} because {{AllocatorPerContext}} 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)