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https://issues.apache.org/jira/browse/IMPALA-8316?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16796501#comment-16796501
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ASF subversion and git services commented on IMPALA-8316:
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Commit 4743f5edb93905d9feff2b5db5b6e4741c972449 in impala's branch
refs/heads/master from Lars Volker
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=4743f5e ]
Revert "IMPALA-8316. Update re2 to the latest version"
This uses a toolchain version that depends on Ubuntu 18.04. We'll have to
re-submit once the toolchain has been published for that OS, too.
This reverts commit 2014199c80c6c74ba4e46139337cd41e1089cc9e.
Change-Id: I4fd16048cf5d89d76bc00ca2837cb11829e30192
Reviewed-on: http://gerrit.cloudera.org:8080/12790
Reviewed-by: Lars Volker <[email protected]>
Tested-by: Lars Volker <[email protected]>
> Update re2 to avoid lock contention
> -----------------------------------
>
> Key: IMPALA-8316
> URL: https://issues.apache.org/jira/browse/IMPALA-8316
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Major
> Labels: perf
> Fix For: Impala 3.3.0
>
>
> I ran the following test query and found that it spent a lot of time in lock
> contention within the re2 library:
> ```select sum(l_linenumber) from item_20x where
> regexp_extract(l_shipinstruct, '.*E', 0) like '%E' ;```
> I think this lock contention would happen on any regex that involves
> backtracking. This was fixed in the re2 library upstream in
> https://github.com/google/re2/commit/eb00dfdd82015be22086cacc6bf830f72a10e2bc#diff-a60a8d25ed15adf68b94c85775fd3cf7
> We should consider upgrading re2 to the latest release, or if not that, at
> least cherry-picking this perf fix.
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