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