hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Xiaobing Zhou (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9741) Refactor MetaStoreDirectSql constructor by removing DB queries out of critical section
Date Tue, 24 Feb 2015 22:32:04 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14335584#comment-14335584
] 

Xiaobing Zhou commented on HIVE-9741:
-------------------------------------

Thanks [~sershe] for review. If setDbANSIMode() call is moved to somewhere like patch V4.
DB query within critical section still can not be avoided as the stack trace shows. This is
a problem, do you have any comments?

MetaStoreDirectSql.determineDbType(...)
MetaStoreDirectSql.MetaStoreDirectSql(...)
ObjectStore.initialize(...)
ObjectStore.setConf(…)


DB type detections is actually manually tested agains different backend, works well.

> Refactor MetaStoreDirectSql constructor by removing DB queries out of critical section
> --------------------------------------------------------------------------------------
>
>                 Key: HIVE-9741
>                 URL: https://issues.apache.org/jira/browse/HIVE-9741
>             Project: Hive
>          Issue Type: Bug
>          Components: Metastore
>    Affects Versions: 1.0.0
>            Reporter: Xiaobing Zhou
>            Assignee: Xiaobing Zhou
>         Attachments: HIVE-9741.1.patch, HIVE-9741.2.patch, HIVE-9741.3.patch, HIVE-9741.4.patch
>
>
> MetaStoreDirectSql constructor is querying DB to determine dbType, which leads to too
many DB queries to make megastore slow as ObjectStore.setConf might be called frequently.
Moreover, ObjectStore.setConf begins/ends with lock acquire/release, if the underlying DB
hangs somehow, lock is never released and all hereafter incoming requests are blocked.
> Two points:
> 1. Using getProductName based JDBC driver to get dbType info.
> 2. Since metastore auto-creaton is disabled by default, it'd better bypass ensureDbInit()
and runTestQuery() in order to avoid DB queries within critical section of setConf.
> Here’s stack trace:
> MetaStoreDirectSql.determineDbType(...)
> MetaStoreDirectSql.MetaStoreDirectSql(...)
> ObjectStore.initialize(...)
> ObjectStore.setConf(…)



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

Mime
View raw message