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From "Eugene Koifman (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-13249) Hard upper bound on number of open transactions
Date Thu, 12 May 2016 18:21:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-13249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15281880#comment-15281880
] 

Eugene Koifman commented on HIVE-13249:
---------------------------------------

what I meant is
{noformat}
public OpenTxnsResponse openTxns(OpenTxnRequest rqst) throws MetaException {
384	    if (openTxnsCounter == null) {
synchronzied(TxnHandler.class) {
385	      try {
	    if (openTxnsCounter == null) {
386	        startHouseKeeperService(conf, Class.forName("org.apache.hadoop.hive.ql.txn.AcidOpenTxnsCounterService"));
}
387	      } catch (Exception e) {
388	        throw new MetaException(e.getMessage());
389	      }
}
390	    }
{noformat}
http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html


One more thing:
startHouseKeeperService() catches Exception and logs but when openTxns() calls startHouseKeeperService()
it catches and rethrows.

Seems contradictory.  Did you want to fail all txns if this service is not available or make
best effort?


> Hard upper bound on number of open transactions
> -----------------------------------------------
>
>                 Key: HIVE-13249
>                 URL: https://issues.apache.org/jira/browse/HIVE-13249
>             Project: Hive
>          Issue Type: Improvement
>          Components: Transactions
>    Affects Versions: 2.0.0
>            Reporter: Wei Zheng
>            Assignee: Wei Zheng
>         Attachments: HIVE-13249.1.patch, HIVE-13249.2.patch, HIVE-13249.3.patch, HIVE-13249.4.patch,
HIVE-13249.5.patch, HIVE-13249.6.patch, HIVE-13249.7.patch, HIVE-13249.8.patch, HIVE-13249.9.patch
>
>
> We need to have a safeguard by adding an upper bound for open transactions to avoid huge
number of open-transaction requests, usually due to improper configuration of clients such
as Storm.
> Once that limit is reached, clients will start failing.



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