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From "Christian Grobmeier" <grobme...@gmail.com>
Subject Re: [COMPRESS] performance improvement in Ant's ZipOutputStream
Date Wed, 16 Jul 2008 13:26:44 GMT
Hi Stefan,
compress is a component of the commons-sandbox project:
https://issues.apache.org/jira/secure/IssueNavigator.jspa?reset=true&mode=hide&pid=12310491&sorter/order=DESC&sorter/field=priority&resolution=-1&component=12311183

@Torsten: i will prepare a patch for the redesign branch.

On Wed, Jul 16, 2008 at 3:20 PM, Stefan Bodewig <bodewig@apache.org> wrote:

> Hi all,
>
> I couldn't find a JIRA for compress so I'm posting it here.
>
> We had a bug report against Ant's ZipOutputStream that showed that the
> class had a way worse performance compared to java.util.zip's cousin
> when it was used to compress big files.  See
> https://issues.apache.org/bugzilla/show_bug.cgi?id=45396
>
> Attached to this report is a small test class that could easily be
> adapted to the compress library.
>
> It turns out that java.util.Deflater doesn't like to see big arrays
> passed into its setInput method and the original reporter says
> OpenJDK's code would split the input into 512 byte chunks.  While I
> didn't verify the OpenJDK code I went looking into zlib and InfoZIP
> and at least InfoZIP's zipup.c uses smaller chunks (between 2kB and
> 16kB) as well when compressing files.
>
> The change I've committed
>
> http://svn.apache.org/viewvc/ant/core/trunk/src/main/org/apache/tools/zip/ZipOutputStream.java?r1=579278&r2=677272&pathrev=677272
> sped up the test by a factor of 40 on my machine.
>
> It won't have any effect on Ant since <zip> has always split up the
> file's content before writing it to the archive, but it would affect
> other direct users of our API - and would probably benefit the
> compress component for just that reason as well.
>
> Stefan
>
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