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From "Uli Bubenheimer (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IO-355) IOUtils read() and skip() methods are performance hogs
Date Wed, 31 Oct 2012 20:08:12 GMT

    [ https://issues.apache.org/jira/browse/IO-355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13488179#comment-13488179
] 

Uli Bubenheimer commented on IO-355:
------------------------------------

Yes, the API contract is a little different than the original skip. The problem is that it
causes skips and reads with skips to be needlessly slow in many cases. Anyone using these
general-purpose APIs suddenly has a millstone on their foot without noticing.
                
> IOUtils read() and skip() methods are performance hogs
> ------------------------------------------------------
>
>                 Key: IO-355
>                 URL: https://issues.apache.org/jira/browse/IO-355
>             Project: Commons IO
>          Issue Type: Bug
>          Components: Utilities
>    Affects Versions: 2.3, 2.4
>            Reporter: Uli Bubenheimer
>
> IOUtils.skip(InputStream, long) and IOUtils.skip(Reader, long) have the worst possible
performance as they always use read() on the input instead of using skip(). In many cases,
using skip() from a subclass of InputStream is much faster than read(), as the skip() can
be implemented via a disk seek.
> The IOUtils.skip() methods are used in the read() methods of IOUtils and their similarly
named siblings, so they tend to bring down the performance of all reads that involve a skip.
> Case in point: I have observed this performance degradation with Java 7 on Windows 7.
A series of consecutive reads on a large file on disk that involved skips changed my performance
from 30 secs as my baseline to 10 minutes after starting to use IOUtils.read().

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