hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-13920) LLAP: pre-populate CVB cache
Date Thu, 02 Jun 2016 06:21:59 GMT

    [ https://issues.apache.org/jira/browse/HIVE-13920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15311812#comment-15311812
] 

Gopal V commented on HIVE-13920:
--------------------------------

Preallocating might actually allocate large number of arrays without actual need - a 10,000
row split shouldn't need 128 vector batches pre-created and adding to the garbage.

The allocation is currently inside the actual reader inner loop, which is a problem because
for the first 128 invocations (& more), the allocation is actually performed.

The 128x more allocations than the regular Tez codepath is the problem, moving it around to
a different part of code doesn't fix the actual perf issue.

> LLAP: pre-populate CVB cache
> ----------------------------
>
>                 Key: HIVE-13920
>                 URL: https://issues.apache.org/jira/browse/HIVE-13920
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Sergey Shelukhin
>
> To avoid allocations on the main path, we should pre-populate the CVB cache. The main
difficulty is propagating column indexes earlier to allocate correct vectors.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message