[jira] [Commented] (TRAFODION-2011) better logging or exception messaging for getScanner issue due to lease timeout

["liu ming (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TRAFODION-2011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15320615#comment-15320615 ] 

liu ming commented on TRAFODION-2011:
-------------------------------------

this is due to transaction lease timeout. And executor doesn't know, so continue to do scan, but the cleanup chore already reclaime the scanner and report this error.
So to fix this, one must correctly handle the transaction lease timeout.

> better logging or exception messaging for getScanner issue due to lease timeout
> -------------------------------------------------------------------------------
>
>                 Key: TRAFODION-2011
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-2011
>             Project: Apache Trafodion
>          Issue Type: Improvement
>            Reporter: liu ming
>            Assignee: liu ming
>
> When an active transaction is too long, its lease will timeout. And the transaction will be retired internally, however, the client doesn't know and still issue new get/put operations, and will get strange exception, which is hard to understand.
> It will be better to enhance the error message or logging to help identify the issue.
> Reproduce:
> simulate a long transaction, 
> >begin;
> wait for 2 hours, or change the hbase.transaction.lease.timeout to shorter timeout.
> >do an update;
> some error like this, it is confusing:
> *** ERROR[8448] Unable to access Hbase interface. Call to ExpHbaseInterface::nextRow returned error HBASE_ACCESS_ERROR(-706). Cause:
> java.util.concurrent.ExecutionException: java.io.IOException: PerformScan error on coprocessor call, scannerID: 1 java.io.IOException: performScan encountered Exception txID: 25769804282 Exception: org.apache.hadoop.hbase.UnknownScannerException: TrxRegionEndpoint getScanner - scanner id 1, already closed?
> java.util.concurrent.FutureTask.report(FutureTask.java:122)
> java.util.concurrent.FutureTask.get(FutureTask.java:188)
> org.trafodion.sql.HTableClient.fetchRows(HTableClient.java:1251)
>  



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