[jira] [Assigned] (HIVE-14524) BaseSemanticAnalyzer may leak HMS connection

["Wei Yan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-14524?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wei Yan reassigned HIVE-14524:
------------------------------

    Assignee: Wei Yan  (was: Chao Sun)

> BaseSemanticAnalyzer may leak HMS connection
> --------------------------------------------
>
>                 Key: HIVE-14524
>                 URL: https://issues.apache.org/jira/browse/HIVE-14524
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2
>    Affects Versions: 2.2.0
>            Reporter: Chao Sun
>            Assignee: Wei Yan
>
> Currently {{BaseSemanticAnalyzer}} keeps a copy of thread-local {{Hive}} object to connect to HMS. However, in some cases Hive may overwrite the existing {{Hive}} object:
> {{Hive#getInternal}}:
> {code}
>   private static Hive getInternal(HiveConf c, boolean needsRefresh, boolean isFastCheck,
>       boolean doRegisterAllFns) throws HiveException {
>     Hive db = hiveDB.get();
>     if (db == null || !db.isCurrentUserOwner() || needsRefresh
>         || (c != null && db.metaStoreClient != null && !isCompatible(db, c, isFastCheck))) {
>       return create(c, false, db, doRegisterAllFns);
>     }
>     if (c != null) {
>       db.conf = c;
>     }
>     return db;
>   }
> {code}
> *This poses an potential problem*: if one first instantiates a {{BaseSemanticAnalyzer}} object with the current {{Hive}} object (let's call it A), and for some reason A is overwritten by B with the code above, then {{BaseSemanticAnalyzer}} may keep using A to contact HMS, which will leak connections.
> This can be reproduced by the following steps:
> 1. open a session
> 2. execute some simple query such as {{desc formatted src}}
> 3. change a metastore property (I know, this is not a perfect example...), for instance: {{set hive.txn.timeout=500}}
> 4. run another command such as {{desc formatted src}} again
> Notice that in step 4), since a metavar is changed the {{isCompatible}} will return false, and hence a new {{Hive}} object is created. As result, you'll observe in the HS2 log that an connection has been leaked.



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