[jira] [Commented] (HIVE-14168) Avoid serializing all parameters from HiveConf.java into in-memory HiveConf instances

["Siddharth Seth (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-14168?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15368644#comment-15368644 ] 

Siddharth Seth commented on HIVE-14168:
---------------------------------------

Any thoughts on this ?

> Avoid serializing all parameters from HiveConf.java into in-memory HiveConf instances
> -------------------------------------------------------------------------------------
>
>                 Key: HIVE-14168
>                 URL: https://issues.apache.org/jira/browse/HIVE-14168
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Siddharth Seth
>            Priority: Critical
>
> All non-null parameters from HiveConf.java are explicitly set in each HiveConf instance.
> {code}
> // Overlay the ConfVars. Note that this ignores ConfVars with null values
>     addResource(getConfVarInputStream());
> {code}
> This unnecessarily bloats each Configuration object - 400+ conf variables being set instead of probably <30 which would exist in hive-site.xml.
> Looking at a HS2 heapdump - HiveConf is almost always the largest component by a long way. Conf objects are also serialized very often - transmitting lots of unneeded variables (serialized Hive conf is typically 1000+ variables - due to Hadoop injecting it's configs into every config instance).
> As long as HiveConf.get() is the approach used to read from a config - this is avoidable. Hive code itself should be doing this.
> This would be a potentially incompatible change for UDFs and other plugins which have access to a Configuration object.
> I'd suggest turning off the insert by default, and adding a flag to control this.



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