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From "Sebb (JIRA)" <>
Subject [jira] [Commented] (IO-355) IOUtils read() and skip() methods are performance hogs
Date Wed, 31 Oct 2012 20:47:12 GMT


Sebb commented on IO-355:

bq. Make sure to change the javadoc for all the read and readFully methods as well

Did you mean skip and skipFully?
The read and readFully methods use the implementation provided, so I don't see how they can
be less performant.

bq. Seems to set a bad precedent for usability of Apache Commons.

The point of the IOUtils#skip() methods is to guarantee that the correct number of bytes/chars
is skipped.
This does not not appear to be possible using the subclass skip() implementations for the
reasons already given.
> IOUtils read() and skip() methods are performance hogs
> ------------------------------------------------------
>                 Key: IO-355
>                 URL:
>             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

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