Thai Bui updated HIVE-17502:
    Attachment: HIVE-17502.3.patch

> Reuse of default session should not throw an exception in LLAP w/ Tez
> ---------------------------------------------------------------------
>                 Key: HIVE-17502
>                 URL: https://issues.apache.org/jira/browse/HIVE-17502
>             Project: Hive
>          Issue Type: Bug
>          Components: llap, Tez
>    Affects Versions: 2.1.1, 2.2.0
>         Environment: HDP, Hue 4
>            Reporter: Thai Bui
>            Assignee: Thai Bui
>            Priority: Major
>             Fix For: 3.1.0
>         Attachments: HIVE-17502.2.patch, HIVE-17502.3.patch, HIVE-17502.patch
> Hive2 w/ LLAP on Tez doesn't allow a currently used, default session to be 
> skipped mostly because of this line 
> https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/exec/tez/TezSessionPoolManager.java#L365.
> However, some clients such as Hue 4, allow multiple sessions to be used per 
> user. Under this configuration, a Thrift client will send a request to either 
> reuse or open a new session. The reuse request could include the session id 
> of a currently used snippet being executed in Hue, this causes HS2 to throw 
> an exception:
> {noformat}
> 2017-09-10T17:51:36,548 INFO  [Thread-89]: tez.TezSessionPoolManager 
> (TezSessionPoolManager.java:canWorkWithSameSession(512)) - The current user: 
> hive, session user: hive
> 2017-09-10T17:51:36,549 ERROR [Thread-89]: exec.Task 
> (TezTask.java:execute(232)) - Failed to execute tez graph.
> org.apache.hadoop.hive.ql.metadata.HiveException: The pool session 
> sessionId=5b61a578-6336-41c5-860d-9838166f97fe, queueName=llap, user=hive, 
> doAs=false, isOpen=true, isDefault=true, expires in 591015330ms should have 
> been returned to the pool
>       at 
> org.apache.hadoop.hive.ql.exec.tez.TezSessionPoolManager.canWorkWithSameSession(TezSessionPoolManager.java:534)
>  ~[hive-exec-]
>       at 
> org.apache.hadoop.hive.ql.exec.tez.TezSessionPoolManager.getSession(TezSessionPoolManager.java:544)
>  ~[hive-exec-]
>       at org.apache.hadoop.hive.ql.exec.tez.TezTask.execute(TezTask.java:147) 
> [hive-exec-]
>       at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:197) 
> [hive-exec-]
>       at 
> org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:100) 
> [hive-exec-]
>       at org.apache.hadoop.hive.ql.exec.TaskRunner.run(TaskRunner.java:79) 
> [hive-exec-]
> {noformat}
> Note that every query is issued as a single 'hive' user to share the LLAP 
> daemon pool, a set of pre-determined number of AMs is initialized at setup 
> time. Thus, HS2 should allow new sessions from a Thrift client to be used out 
> of the pool, or an existing session to be skipped and an unused session from 
> the pool to be returned. The logic to throw an exception in the  
> `canWorkWithSameSession` doesn't make sense to me.
> I have a solution to fix this issue in my local branch at 
> https://github.com/thaibui/hive/commit/078a521b9d0906fe6c0323b63e567f6eee2f3a70.
>  When applied, the log will become like so
> {noformat}
> 2017-09-10T09:15:33,578 INFO  [Thread-239]: tez.TezSessionPoolManager 
> (TezSessionPoolManager.java:canWorkWithSameSession(533)) - Skipping default 
> session sessionId=6638b1da-0f8a-405e-85f0-9586f484e6de, queueName=llap, 
> user=hive, doAs=false, isOpen=true, isDefault=true, expires in 591868732ms 
> since it is being used.
> {noformat}
> A test case is provided in my branch to demonstrate how it works. If possible 
> I would like this patch to be applied to version 2.1, 2.2 and master. Since 
> we are using 2.1 LLAP in production with Hue 4, this patch is critical to our 
> success.
> Alternatively, if this patch is too broad in scope, I propose adding an 
> option to allow "skipping of currently used default sessions". With this new 
> option default to "false", existing behavior won't change unless the option 
> is turned on.
> I will prepare an official path if this change to master &/ the other 
> branches is acceptable. I'm not an contributor &/ committer, this will be my 
> first time contributing to Hive and the Apache foundation. Any early review 
> is greatly appreciated, thanks!

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