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From "Nathan Beyer (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (HARMONY-630) Performance improvement for BufferedReader and LineNumberReader classes
Date Wed, 19 Jul 2006 01:51:14 GMT
     [ http://issues.apache.org/jira/browse/HARMONY-630?page=all ]

Nathan Beyer resolved HARMONY-630.

    Resolution: Won't Fix

I'm marking this as "Won't Fix" since this change only provides minor improvements in very
specific scenarios and seems to show degradations in other scenarios.

> Performance improvement for BufferedReader and LineNumberReader classes
> -----------------------------------------------------------------------
>                 Key: HARMONY-630
>                 URL: http://issues.apache.org/jira/browse/HARMONY-630
>             Project: Harmony
>          Issue Type: Improvement
>          Components: Classlib
>            Reporter: Vladimir Strigun
>         Assigned To: Nathan Beyer
>            Priority: Minor
>         Attachments: Harmony-630.patch
> Analysis of BufferedReader and LineNumberReader was made by our team. These classes are
widely used and it's recommended, for instance, that any character IO should go through BufferedReader
for better performance. Therefore it should perform well and should not itself be a bottleneck.

> We have identified opportunity to increase performance of mentioned classes. Publicly
available bench DaCapo[1] was used for performance measurement and we found that DaCapo:hsqldb
benchmark performance can be improved within small modification of java.io.BufferedReader
and java.io.LineNumberReader classes. Main idea of the patch (I will attach it soon) is to
remove StringBuilder allocation from "malloc"-hot methods readLine. 
> Here is result of DaCapo execution with patched and original versions of classlib+J9:
> Build	Dacapo: fop	Dacapo: hsqldb	Dacapo: xalan	Dacapo: chart	
> original	712.020	27232.647	4201.449	22573.192	
> patched	715.152	26703.966	4161.018	22580.771	
> [1] http://www-ali.cs.umass.edu/DaCapo/gcbm.html

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