[teiid-issues] [JBoss JIRA] (TEIID-3921) Accumulo translator doesn't end query execution when there are no tablet servers

[Jan Stastny (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-3921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13152482#comment-13152482 ] 

Jan Stastny commented on TEIID-3921:
------------------------------------

Wouldn't it be sufficient to get tablet server's location? Then we could maybe "ping" it to find out, whether the port is at least opened at the destination.

The Accumulo API could be helpful there, when regarding the [ZooKeeperInstance|https://accumulo.apache.org/1.5/apidocs/org/apache/accumulo/core/client/ZooKeeperInstance.html] class, which offers getRootTabletLocation() method, returning location in 'hostname:port' form. 

I expect that if the "There are no tablet servers" warning appears, there is no root tablet, or if this still returns an address, it would be unreachable, if the host was down.

> Accumulo translator doesn't end query execution when there are no tablet servers
> --------------------------------------------------------------------------------
>
>                 Key: TEIID-3921
>                 URL: https://issues.jboss.org/browse/TEIID-3921
>             Project: Teiid
>          Issue Type: Bug
>          Components: Misc. Connectors
>    Affects Versions: 8.12.3
>            Reporter: Jan Stastny
>            Assignee: Steven Hawkins
>
> Teiid accumulo translator doesn't interrupt query execution when the accumulo instance is not running.
> There might be a situation that Zookeeper instance is running, but Accumulo is not.
> The translator, even though there is no tablet server entry in zookeeper, for given accumulo instance, executes the query. The query is running until query timeout exceeds. There is no indication of the fact, that accumulo tablet server is not present/responding except for
> {code}
> 09:25:46,539 WARN  [org.apache.accumulo.core.client.impl.ServerClient] (Worker3_QueryProcessorQueue21) There are no tablet servers: check that zookeeper and accumulo are running.
> {code}
> There might be even situation, that Accumulo stopped in unusual way and didn't alter the tablet server information in Zookeeper, this way, there is a tablet server entry present in Zookeeper, but the tablet server is in fact not running. So Teiid should check the tablet server's address which received from Zookeeper.
> Interesting to note is the fact, that the same problem can be examined in accumulo's shell:
> {code}
> $ bin/accumulo shell -u root
> Password: ******
> 2016-01-22 10:02:05,604 [impl.ServerClient] WARN : There are no tablet servers: check that zookeeper and accumulo are running.
> {code}
> and then the shell hangs. Teiid needs to overcome this limitation.



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