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https://issues.apache.org/jira/browse/COMPRESS-466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16641482#comment-16641482
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Jakob Sultan Ericsson commented on COMPRESS-466:
------------------------------------------------

One thing though? Why does {{getRawInputStream()}} return null in this case?
 Isn't basically same as {{getInputStream()}}

On thing that might not be totally related to this, why is 
{{ZipArchiveEntry.getLocalHeaderOffset()}} protected?
 We might have problems with taking the X seconds (18 in my test) penalty for 
opening the file and reading it every time. If {{getLocalHeaderOffset}} is 
public I can basically find out where the data starts and decompress it myself.

> Opening of a very large zip file is extremely slow compared to 
> java.util.zip.ZipFile
> ------------------------------------------------------------------------------------
>
>                 Key: COMPRESS-466
>                 URL: https://issues.apache.org/jira/browse/COMPRESS-466
>             Project: Commons Compress
>          Issue Type: Improvement
>          Components: Compressors
>    Affects Versions: 1.18
>         Environment: Tested both on Linux and OSX 10.13.6.
>            Reporter: Jakob Sultan Ericsson
>            Priority: Major
>             Fix For: 1.19
>
>
> We have a quite large zip file 35 gb and try to open this with ZipFile. 
> {code:java}
>         try (ZipFile zf = new ZipFile(new File("35gb.zip"))) {
>             System.out.println("File opened..." + (System.currentTimeMillis() 
> - start));
>         }
> {code}
> This code takes about 300 000 - 400 000 ms (5-6 minutes).
> If I run this with JDK-builtin java.util.zip.ZipFile, same code takes 300 ms 
> (less than a second). 
> I'm not totally sure what it is the problem but I did some debugging and 
> basically all time is spent in
> {code:java}
>     private void resolveLocalFileHeaderData(final Map<ZipArchiveEntry, 
> NameAndComment> entriesWithoutUTF8Flag)
> {code}
> Anything that can be done to improve this?



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