Mailing-List: contact issues-help@commons.apache.org; run by ezmlm
Precedence: bulk
Reply-To: issues@commons.apache.org
Date: Wed, 31 Oct 2012 21:33:12 +0000 (UTC)
From: "Uli Bubenheimer (JIRA)" <jira@apache.org>
To: issues@commons.apache.org
Message-ID: <1616077910.53186.1351719192370.JavaMail.jiratomcat@arcas>
In-Reply-To: <767287737.51026.1351700832285.JavaMail.jiratomcat@arcas>
Subject: [jira] [Updated] (IO-355) IOUtils copyLarge() and skip() methods
 are performance hogs
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


     [ https://issues.apache.org/jira/browse/IO-355?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Uli Bubenheimer updated IO-355:
-------------------------------

    Description: 
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 also used in the copyLarge() methods that involve a skip.

Case in point: I have observed this performance degradation with Java 7 on Windows 7. A series of consecutive copyLarge() invocations 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.copyLarge().

  was:
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().

    
> IOUtils copyLarge() 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 also used in the copyLarge() methods that involve a skip.
> Case in point: I have observed this performance degradation with Java 7 on Windows 7. A series of consecutive copyLarge() invocations 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.copyLarge().

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira