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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HIVE-20893) BloomK Filter probing method is not thread safe
Date Thu, 08 Nov 2018 19:31:01 GMT

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

Gopal V edited comment on HIVE-20893 at 11/8/18 7:30 PM:
---------------------------------------------------------

[~bslim]: The masks array loop can be unrolled to remove the array variable entirely - the
array variable made more sense when the cache width was not hard-coded as 8. 

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


was (Author: gopalv):
[~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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