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https://issues.apache.org/jira/browse/HIVE-584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12724645#action_12724645
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Edward Capriolo commented on HIVE-584:
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I ran into a few of these issues with HWI, so I feel your pain. Passing the
conf around is very cumbersome. I remember my case I wanted to get the Conf
from a CLI session state. It would be nice if each object stored the conf as a
private variable with a getter. It would help out the web interface code a lot.
The implementation above seems to make sense.
> Clean up global and ThreadLocal variables in Hive
> -------------------------------------------------
>
> Key: HIVE-584
> URL: https://issues.apache.org/jira/browse/HIVE-584
> Project: Hadoop Hive
> Issue Type: Improvement
> Affects Versions: 0.3.0, 0.3.1
> Reporter: Zheng Shao
>
> Currently in Hive code there are several global and ThreadLocal variables
> that need to be cleaned.
> Specifically, the following classes are involved:
> 1. HiveConf: contains hive configurations (and a classloader)
> 2. Hive class: contains a static member Hive db. Hive class contains a member
> HiveConf conf, as well as a ThreadLocal storage of IMetaStoreClient.
> 3. SessionState: contains a static ThreadLocal storage of SessionState.
> SessionState class contains a Hive db, a HiveConf conf, a history logger, and
> a bunch of standard input/output streams
> 4. CliSessionState: SessionState plus some command options and the command
> file name.
> 5. All classes that try to get Hive db or HiveConf from global static Hive
> db, or SessionState.
> There are several problems with the current design. To name a few:
> 1. SessionState instances are ThreadLocal, but SessionState contains Hive db
> which also contains ThreadLocal storage. Not sure a db can be shared across
> different threads or not? What is the global static Hive db?
> 2. We pass HiveConf and Hive db in two ways to classes like Task: Sometimes
> through initialize(), sometimes through SessionState. This complicates the
> code a lot. It's hard to know which HiveConf and which db we should use.
> We need to think about a better way to do it.
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