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From "Hive QA (JIRA)" <>
Subject [jira] [Commented] (HIVE-20682) Async query execution can potentially fail if shared sessionHive is closed by master thread.
Date Sun, 28 Oct 2018 15:18:00 GMT


Hive QA commented on HIVE-20682:

Here are the results of testing the latest attachment:

{color:red}ERROR:{color} -1 due to build exiting with an error

Test results:
Console output:
Test logs:

Executing org.apache.hive.ptest.execution.TestCheckPhase
Tests exited with: Exception: Patch URL
was found in seen patch url's cache and a test was probably run already on it. Aborting...

This message is automatically generated.

ATTACHMENT ID: 12945741 - PreCommit-HIVE-Build

> Async query execution can potentially fail if shared sessionHive is closed by master
> --------------------------------------------------------------------------------------------
>                 Key: HIVE-20682
>                 URL:
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2
>    Affects Versions: 3.1.0, 4.0.0
>            Reporter: Sankar Hariappan
>            Assignee: Sankar Hariappan
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: HIVE-20682.01.patch, HIVE-20682.02.patch, HIVE-20682.03.patch, HIVE-20682.04.patch
> *Problem description:*
> The master thread initializes the *sessionHive* object in *HiveSessionImpl* class when we
open a new session for a client connection and by default all queries from this connection shares
the same sessionHive object. 
> If the master thread executes a *synchronous* query, it closes the sessionHive object
(referred via thread local hiveDb) if  {{Hive.isCompatible}} returns false and sets new Hive
object in thread local HiveDb but doesn't change the sessionHive object in the session. Whereas,
*asynchronous* query execution via async threads never closes the sessionHive object and
it just creates a new one if needed and sets it as their thread local hiveDb.
> So, the problem can happen in the case where an *asynchronous* query is being executed
by async threads refers to sessionHive object and the master thread receives a *synchronous*
query that closes the same sessionHive object. 
> Also, each query execution overwrites the thread local hiveDb object to sessionHive object
which potentially leaks a metastore connection if the previous synchronous query execution
re-created the Hive object.
> *Possible Fix:*
> The *sessionHive* object could be shared my multiple threads and so it shouldn't be allowed
to be closed by any query execution threads when they re-create the Hive object due to changes
in Hive configurations. But the Hive objects created by query execution threads should be
closed when the thread exits.
> So, it is proposed to have an *isAllowClose* flag (default: *true*) in Hive object which
should be set to *false* for *sessionHive* and would be forcefully closed when the session
is closed or released.
> cc [~pvary]

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