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From "Carl Steinbach (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-4239) Remove lock on compilation stage
Date Fri, 29 May 2015 10:08:17 GMT

    [ https://issues.apache.org/jira/browse/HIVE-4239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14564517#comment-14564517
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Carl Steinbach commented on HIVE-4239:
--------------------------------------

A couple comments on the patch:
* Would you mind changing the name of the new configuration property to 'hive.driver.parallel.compilation'?
The only reference to this config property is located in the Driver class, and both Driver
and SessionState predate HiveServer2 by several years. Driver and SessionState were used by
HiveServer1 and continue to be used by the HiveCli, and I know that there are at least a couple
third-party libraries out there that attempt to support concurrency by scheduling queries
across a pool of Driver objects. In other words, this property changes the behavior of a class
which is not part of HiveServer2, and also has the potential to change the behavior of other
user-facing interfaces built on top of Driver which are also not part of HiveServer2. I also
hope that at some point the Driver and SessionState classes will go away completely, at which
point we can deprecate and remove this property, but only if it references "driver".
* I think the docstring for the new property could use some wordsmithing: "Whether to enable
parallel compilation on HiveServer2. _Disable as a workaround for future bugs._" The last
sentence isn't going to inspire much confidence in users about either the quality of the product
or the development team that produced it. 
* In order to enable this feature by default I think we need to be pretty confident that parallel
compilation works. The additional parallel test coverage included in this patch is a great
start, but I think it falls well short of being comprehensive. I mentioned in an earlier comment
that code already exists for running qfile tests in parallel on top of HiveServer2. Why not
re-enable this?


> Remove lock on compilation stage
> --------------------------------
>
>                 Key: HIVE-4239
>                 URL: https://issues.apache.org/jira/browse/HIVE-4239
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2, Query Processor
>            Reporter: Carl Steinbach
>            Assignee: Sergey Shelukhin
>         Attachments: HIVE-4239.01.patch, HIVE-4239.patch
>
>




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