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From "Uli Bubenheimer (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IO-355) IOUtils read() and skip() methods are performance hogs
Date Wed, 31 Oct 2012 16:27:12 GMT
Uli Bubenheimer created IO-355:
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             Summary: 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: 2.4, 2.3
            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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