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Posted to issues-all@impala.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2019/03/16 04:17:00 UTC

[jira] [Created] (IMPALA-8316) Update re2 to avoid lock contention

Todd Lipcon created IMPALA-8316:
-----------------------------------

             Summary: 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


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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