Test_SplitReadOnlySpan

Summary

• Visual Studio 2019
• .NET Core 3.1
• Enable nullable option
• Use BenchmarkDotNet

Benchmarking SpanExtensions.SplitToRanges<T> extension methods.

These methods splits ReadOnlySpan<T> or Span<T> by a separator(s), and returns List<Range> that means each split range.

Benchmark methods

All following objects and methods are implemented on BenchmarkMethods class.

private static readonly string[] LineBreaks = { "\r\n", "\n", "\r" };

// Multi-line string. Lines are separated using '\n'.
private string textWithNewLine = @"";

// Multi-line string. Lines are separated using LineBreaks elements.
private string textWithLineBreaks = @"";

// Number of lines of texts for Setup() method. (Assigned by BenchmarkDotNet)
[Params(1, 10, 100, 1000, 10000)]
public int Line { get; set; }

// Make N-line texts. (Called by BenchmarkDotNet before benchmarking)
[GlobalSetup]
public void Setup()
{
    this.textWithNewLine = MakeString(this.Line, "\n");
    this.textWithLineBreaks = MakeString(this.Line, LineBreaks);
}

• String_SplitNewLine
  • Split textWithNewLine to string[] using string.Split('\n').
• Span_SplitNewLine
  1. Split textWithNewLine.AsSpan() to List<Range> using ReadOnlySpan<char>.SplitToRanges('\n').
  2. Create string[] using List<Range>.
• String_SplitLineBreaks
  • Split textWithLineBreaks to string[] using string.Split(LineBreaks, StringSplitOptions.None).
• Span_SplitLineBreaks
  1. Split textWithLineBreaks.AsSpan() to List<Range> using ReadOnlySpan<char>.SplitToRanges(LineBreaks).
  2. Create string[] using List<Range>.

Benchmark results (on ruche7's PC)

ReadOnlySpan<char>.SplitToRanges is faster than string.Split in most cases.

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.18363.1049 (1909/November2018Update/19H2)
Intel Core i7-5820K CPU 3.30GHz (Broadwell), 1 CPU, 12 logical and 6 physical cores
.NET Core SDK=3.1.401
  [Host]     : .NET Core 3.1.7 (CoreCLR 4.700.20.36602, CoreFX 4.700.20.37001), X64 RyuJIT
  DefaultJob : .NET Core 3.1.7 (CoreCLR 4.700.20.36602, CoreFX 4.700.20.37001), X64 RyuJIT

Method	Line	Mean	Error	StdDev	Median	Ratio	RatioSD
String_SplitNewLine	1	95.16 ns	1.981 ns	2.432 ns	95.29 ns	1.00	0.00
Span_SplitNewLine	1	88.02 ns	1.823 ns	3.241 ns	87.28 ns	0.93	0.04
String_SplitLineBreaks	1	535.48 ns	10.543 ns	17.322 ns	524.74 ns	1.00	0.00
Span_SplitLineBreaks	1	164.18 ns	3.299 ns	5.690 ns	163.77 ns	0.31	0.01
String_SplitNewLine	10	1,168.94 ns	22.938 ns	36.382 ns	1,159.28 ns	1.00	0.00
Span_SplitNewLine	10	641.60 ns	12.820 ns	21.063 ns	635.01 ns	0.55	0.03
String_SplitLineBreaks	10	5,866.13 ns	116.753 ns	143.383 ns	5,796.83 ns	1.00	0.00
Span_SplitLineBreaks	10	1,291.84 ns	25.517 ns	37.402 ns	1,286.95 ns	0.22	0.01
String_SplitNewLine	100	15,516.05 ns	307.663 ns	592.763 ns	15,222.39 ns	1.00	0.00
Span_SplitNewLine	100	7,050.35 ns	139.022 ns	203.777 ns	7,031.02 ns	0.45	0.02
String_SplitLineBreaks	100	80,980.63 ns	1,602.805 ns	2,139.698 ns	80,115.99 ns	1.00	0.00
Span_SplitLineBreaks	100	15,043.74 ns	299.639 ns	618.806 ns	14,745.88 ns	0.19	0.01
String_SplitNewLine	1000	531,209.00 ns	10,428.672 ns	20,340.324 ns	525,057.23 ns	1.00	0.00
Span_SplitNewLine	1000	277,541.18 ns	5,548.385 ns	12,859.226 ns	272,262.67 ns	0.52	0.03
String_SplitLineBreaks	1000	2,568,626.85 ns	51,089.372 ns	83,941.303 ns	2,563,442.97 ns	1.00	0.00
Span_SplitLineBreaks	1000	466,290.67 ns	8,680.937 ns	8,120.153 ns	468,105.57 ns	0.18	0.01
String_SplitNewLine	10000	14,966,129.04 ns	298,504.084 ns	482,028.454 ns	14,967,072.66 ns	1.00	0.00
Span_SplitNewLine	10000	12,513,163.83 ns	229,669.429 ns	408,237.177 ns	12,419,979.69 ns	0.84	0.04
String_SplitLineBreaks	10000	35,700,258.00 ns	670,069.094 ns	894,522.994 ns	35,222,568.75 ns	1.00	0.00
Span_SplitLineBreaks	10000	14,255,644.85 ns	277,051.889 ns	447,387.157 ns	14,194,607.81 ns	0.40	0.01