[IO-650] Improve IOUtils performance by increasing DEFAULT_BUFFER_SIZE

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0
• Fix Version/s: 2.7
• Assignee: Unassigned
• Reporter: Brett Lounsbury
• Created: 13/Jan/20 21:57
• Updated: 18/May/20 17:32
• Resolved: 18/May/20 17:32

Description

IOUtils has a 4096B default buffer size that is used by copy() methods (and will be used for contentEquals methods when IO-649 is pulled).  This number should be updated to 8192 for a few reasons:

1. It has a big improvement in performance in my micro-benchmark.  I tested both copy() and contentEquals() with 4K and 8K buffers.  This was done on a Late 2019 Macbook Pro (2.8GHz i7) with a 128MB file loaded into the OS buffer cache.  See below for the test harness used.  Past 8K performance does improve but it begins to experience some diminishing returns and could lead to excessive memory allocation.
2. It mirrors the default buffer size of java.io.Buffered* classes.  This makes buffer sizing consistent regardless of if it is being done internally in the method or externally via a Buffered*.  These classes are used internally in IOUtils as well so the buffer size is not unreasonable.

 

For copy():

Metric	8K Buffer Millisecond	4K Buffer Millisecond	Performance Improvement
AVG	44.2853417	64.2600679	0.31084197
P50	42.692406	62.371984	0.31551951
P90	49.5538826	68.4303876	0.27584975
P99	62.8831473	89.759114	0.29942326
P100	102.563615	177.143364	0.42101351

 

For contentEquals() with IO-649:

Metric	8K Buffer Millisecond	4K Buffer Millisecond	Performance Improvement
AVG	81.5009567	128.497828	0.36574059
P50	78.517749	124.191476	0.36776861
P90	89.9172708	136.779763	0.34261276
P99	125.814333	183.881989	0.31578762
P100	308.936585	559.611217	0.44794426

public static void main(String[] args) throws Exception {
     NullOutputStream nos = NullOutputStream.NULL_OUTPUT_STREAM;
     for (int i = 0; i < 1000; i++) {
         InputStream fis = new FileInputStream(new File("/tmp/random_data"));
         long start = System.nanoTime();
         IOUtils.copy(fis, nos);
         long defaultCopyTime = System.nanoTime() - start;

         fis = new FileInputStream(new File("/tmp/random_data"));

         start = System.nanoTime();
         IOUtils.copy(fis, nos, 8192);
         long bufferSizeSpecifiedCopyTime = System.nanoTime() - start;

         System.out.println(bufferSizeSpecifiedCopyTime + "\t" + defaultCopyTime);
     }
}

public static void main(String[] args) throws Exception {
    for (int i = 0; i < 1000; i++) {
        InputStream fis = new FileInputStream(new File("/tmp/random_data"));
        InputStream fis2 = new FileInputStream(new File("/tmp/random_data"));

        long start = System.nanoTime();
        IOUtils.contentEquals(fis, fis2);
        long defaultContentEqualsTime = System.nanoTime() - start;

        fis = new FileInputStream(new File("/tmp/random_data"));
        fis2 = new FileInputStream(new File("/tmp/random_data"));

         start = System.nanoTime();
         IOUtils.contentEquals(fis, fis2, 8192);
         long bufferSizeSpecifiedContentEqualsTime = System.nanoTime() - start;

         System.out.println(bufferSizeSpecifiedContentEqualsTime + "\t" + defaultContentEqualsTime);

    }

}