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Posted to issues@hive.apache.org by "Gopal V (JIRA)" <ji...@apache.org> on 2018/11/08 19:30:01 UTC

[jira] [Commented] (HIVE-20893) BloomK Filter probing method is not thread safe

    [ https://issues.apache.org/jira/browse/HIVE-20893?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16680228#comment-16680228 ] 

Gopal V commented on HIVE-20893:
--------------------------------

[~bslim]: The masks array loop can be unrolled to remove the array variable entirely - the array variable made more sense when the cache width mattered. 

You might get the performance back, without invoking a synchronized instruction there (the thread local .get).

> BloomK Filter probing method is not thread safe
> -----------------------------------------------
>
>                 Key: HIVE-20893
>                 URL: https://issues.apache.org/jira/browse/HIVE-20893
>             Project: Hive
>          Issue Type: Bug
>          Components: storage-api
>            Reporter: slim bouguerra
>            Priority: Major
>
> As far i can tell this is not an issue for Hive yet (most of the usage of probing seems to be done by one thread at a time) but it is an issue of other users like Druid as per the following issue.[https://github.com/apache/incubator-druid/issues/6546]
> The fix is proposed by the author of [https://github.com/apache/incubator-druid/pull/6584] is to make couple of local fields as ThreadLocals.
> Idea looks good to me and doesn't have any perf drawbacks.
>  



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