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https://issues.apache.org/jira/browse/HIVE-9223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14265151#comment-14265151
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Pala M Muthaia commented on HIVE-9223:
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Yes, single HS2 session that receive multiple queries. I can do that by using
the Cloudera Hue UI for Hadoop. Basically i open multiple tabs after logging in
- and submit queries concurrently. Internally, it submits the queries to HS2
thrift interface using the same session id header/cookie, and HS2 uses the same
session state for both queries, and hit this issue.
Yes this works in mapreduce. Each query, despite being in the same HS2 session,
are submitted as different MR application to YARN naturally, because there is
no notion of application reuse for MR. For Tez, on the other hand, a Tez
application is tied to HS2 session and an attempt to reuse the Tez application
is done (and fails in this case).
> HiveServer2 on Tez doesn't support concurrent queries within one session
> ------------------------------------------------------------------------
>
> Key: HIVE-9223
> URL: https://issues.apache.org/jira/browse/HIVE-9223
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Reporter: Pala M Muthaia
>
> When a user submits multiple queries in the same HS2 session (using thrift
> interface) concurrently, the query goes through the same TezSessionState and
> ends up being submitted to the same Tez AM, and the second query fails with
> the error "App master already running a DAG"
> Is this by design? I looked into the code, and the comments as well as the
> code suggest support only for serial execution of queries within the same
> HiveServer2 session (on tez).
> This works for CLI environment but in a server, it is plausible that client
> sends multiple concurrent queries under the same session (e.g: a web app that
> executes queries for user, such as Cloudera Hue). So shouldn't HS2 on Tez
> implementation support concurrent queries?
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