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Fix it, then Ship it!




Please make sure you don't accidentally create a new CPU performance problem, 
see below.


sentry-hdfs/sentry-hdfs-service/src/main/java/org/apache/sentry/hdfs/PathImageRetriever.java
Lines 83 (patched)
<https://reviews.apache.org/r/61986/#comment260190>

    This StringUtils.countMatches() that looks for a substring, rather than a 
single char, may potentially be rather slow. It's one thing to go through all 
the characters in a string once, and perform == check for each. But it may be 
an order of magnitude slower to repeatedly perform a search for substring 
(unless this is specially optimized). So I highly recommend to check the source 
code of StringUtils.countMatches(), and maybe search for / implement your own 
countMatches(String haystack, char needle)


- Misha Dmitriev


On Aug. 30, 2017, 4:59 a.m., Alexander Kolbasov wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/61986/
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> 
> (Updated Aug. 30, 2017, 4:59 a.m.)
> 
> 
> Review request for sentry, Arjun Mishra, Brian Towles, Misha Dmitriev, Na Li, 
> Sergio Pena, Vamsee Yarlagadda, and Vadim Spector.
> 
> 
> Bugs: SENTRY-1907
>     https://issues.apache.org/jira/browse/SENTRY-1907
> 
> 
> Repository: sentry
> 
> 
> Description
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> 
> SENTRY-1907 Potential memory optimization when handling big full snapshots.
> 
> 
> Diffs
> -----
> 
>   
> sentry-hdfs/sentry-hdfs-service/src/main/java/org/apache/sentry/hdfs/PathImageRetriever.java
>  f1e67ca6e343e4e5dd0c3377c4c6beb19544e3eb 
> 
> 
> Diff: https://reviews.apache.org/r/61986/diff/1/
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Alexander Kolbasov
> 
>

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