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From "Stefan Bodewig (JIRA)" <>
Subject [jira] [Commented] (COMPRESS-215) ZipFile reads up to 64KiB in a sequence of one byte reads
Date Sat, 19 Jan 2013 13:46:12 GMT


Stefan Bodewig commented on COMPRESS-215:

As long as the ZIP format doesn't change your solution should work and in fact speed up reading
Zip32 archives, thanks!
> ZipFile reads up to 64KiB in a sequence of one byte reads
> ---------------------------------------------------------
>                 Key: COMPRESS-215
>                 URL:
>             Project: Commons Compress
>          Issue Type: Improvement
>          Components: Archivers
>    Affects Versions: 1.4.1
>         Environment: JDK 1.7 64-bit, Windows 7
>            Reporter: Robin Power
>            Priority: Minor
>         Attachments: COMPRESS-215.patch
> This relates to a performance improvement.
> When ZipFile is parsing a file it searches for the ZIP64 End Of Central Directory Locator
as a first step to determining if the file is ZIP64 or regular 32 bit. It searches in reverse
for the ZIP64 EOCDL signature from the end of the file reading one byte at a time, potentially
up to about 64KiB.
> This can be an expensive operation, especially if it is not a ZIP64 file, as it will
make over 64000 file reads to determine that the file is not ZIP64.

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