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https://issues.apache.org/jira/browse/IO-649?focusedWorklogId=377699&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-377699
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ASF GitHub Bot logged work on IO-649:
-------------------------------------
Author: ASF GitHub Bot
Created on: 27/Jan/20 15:28
Start Date: 27/Jan/20 15:28
Worklog Time Spent: 10m
Work Description: brettlounsbury commented on issue #101: IO-649 -
Improve the performance of the contentEquals() methods.
URL: https://github.com/apache/commons-io/pull/101#issuecomment-578802448
@garydgregory,
I really appreciate your thorough review of my code. I think at this point
I have addressed your comments, but if you have any others please let me know.
I will add that I made the IOUtils.DEFAULT_BUFFER_SIZE constant package
private (default visibility) so it could be referenced from IOUtils tests so
that I can ensure the logic makes sense around buffer boundaries and I didn't
want to clone that property since it could later be mutated and invalidate some
of the edge condition testing being done.
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Issue Time Tracking
-------------------
Worklog Id: (was: 377699)
Time Spent: 4h 40m (was: 4.5h)
> IOUtils contentEquals method performance improvements
> -----------------------------------------------------
>
> Key: IO-649
> URL: https://issues.apache.org/jira/browse/IO-649
> Project: Commons IO
> Issue Type: Improvement
> Components: Utilities
> Affects Versions: 1.0, 1.1
> Reporter: Brett Lounsbury
> Priority: Major
> Fix For: 2.6
>
> Time Spent: 4h 40m
> Remaining Estimate: 0h
>
>
> contentEquals() internally wraps any given InputStream/Reader in a Buffered
> version (if it is not already buffered) which avoids a lot of IO penalties,
> but then it proceeds to read each byte/character one at a time. This leads
> to significantly more method calls and also a lot of byte -> int casting
> since the read() method returns an int between 0 and 255 instead of returning
> a byte.
>
> I have a change that modifies the contentEquals() methods to internally
> buffer content into a byte/char array and to then do batch comparisons of
> those arrays using Arrays.equals instead of using a BufferedInputStream or
> BufferedReader and making use of the single byte/char read() methods. This
> reduces the number of method invocations by a factor equal to the buffer size
> and avoids casting every byte read to an int.
>
> The following table shows the performance increase over 1000 iterations of
> comparing 2 1GB InputStream of binary data (stored in memory to avoid I/O).
> This test was performed on an EC2 M4.4XL host using Java 1.8.0.232 and there
> was a forced System.gc() between each iteration to avoid GC as a source of
> latency:
> Average: 7236 to 858ms (8.43x speedup)
> P50: 7224 to 856ms (8.44x speedup)
> P90: 7249 to 860ms (8.43x speedup)
> P99: 7410 to 913ms (8.12x speedup)
> P100: 8330 to 1278ms (6.52x speedup)
>
> The following table shows the performance increase over 1000 iterations of
> comparing 2 1GB Reader of character data (stored in memory to avoid I/O).
> This test was performed on an EC2 M4.4XL host using Java 1.8.0.232 and there
> was a forced System.gc() between each iteration to avoid GC as a source of
> latency:
> Average: 11281 to 1737ms (6.50x speedup)
> P50: 11262 to 1735ms (6.49x speedup)
> P90: 11292 to 1741ms (6.49x speedup)
> P99: 11707 to 1774ms (6.60x speedup)
> P100: 12176 to 1884ms (6.46x speedup)
>
>
>
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