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