The following C# code seems to run slower when built with VS2010 than with VS2008: on a Core i5 Win7 x64 8 GB RAM PC, the VS2008 built version sorts strings in about 7.5 seconds, instead the VS2010 built version requires about 9 seconds. Why is that?
Is there anything wrong with my code?
Did the sorting algorithm change in VS2010?
Is there anything different in the underlying CLR that makes the performance worse?
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Linq;
namespace StringSortCSharp
{
/// <summary>
/// Console app to test string sorting performance in C#.
/// </summary>
class Program
{
/// <summary>
/// Displays the first lines from a vector of strings.
/// </summary>
/// <param name="wishedN">Number of lines to display.</param>
/// <param name="lines">Source lines to display.</param>
private static void DisplayFirst(int wishedN, List<string> lines)
{
int n = Math.Min(wishedN, lines.Count);
for (int i = 0; i < n; i++)
{
Console.WriteLine(" " + lines[i]);
}
Console.WriteLine();
}
/// <summary>
/// Used for random permutation.
/// </summary>
private static Random random = new Random();
/// <summary>
/// Computes a random permutation of the input sequence.
///
/// From:
/// http://stackoverflow.com/questions/375351/most-efficient-way-to-randomly-sort-shuffle-a-list-of-integers-in-c-sharp
///
/// </summary>
/// <typeparam name="T">Type stored in the sequences.</typeparam>
/// <param name="sequence">Input sequence.</param>
/// <returns>Random permutation of the input sequence.</returns>
private static IEnumerable<T> RandomPermutation<T>(IEnumerable<T> sequence)
{
T[] retArray = sequence.ToArray();
for (int i = 0; i < retArray.Length - 1; i += 1)
{
int swapIndex = random.Next(i + 1, retArray.Length);
T temp = retArray[i];
retArray[i] = retArray[swapIndex];
retArray[swapIndex] = temp;
}
return retArray;
}
/// <summary>
/// Builds a list of strings used in the performance benchmark.
/// </summary>
/// <returns>Test list of strings.</returns>
private static List<string> BuildTestLines()
{
// Start with "Lorem ipsum", and repeat it several times, adding some suffix strings.
var lorem = new string[]
{
"Lorem ipsum dolor sit amet, consectetuer adipiscing elit.",
"Maecenas porttitor congue massa. Fusce posuere, magna sed",
"pulvinar ultricies, purus lectus malesuada libero,",
"sit amet commodo magna eros quis urna.",
"Nunc viverra imperdiet enim. Fusce est. Vivamus a tellus.",
"Pellentesque habitant morbi tristique senectus et netus et",
"malesuada fames ac turpis egestas. Proin pharetra nonummy pede.",
"Mauris et orci."
};
int repeatCount = 200 * 1000;
Console.Write("Building test strings");
var testLines = new List<string>();
Console.Write(" (total string count = {0})", repeatCount * lorem.Length);
Console.Write("...");
for (int i = 0; i < repeatCount; i++)
{
for (int j = 0; j < lorem.Length; j++)
{
// Add more stuff to Lorem strings
testLines.Add(lorem[j] + " (#" + i + ")");
}
}
Console.WriteLine("done.");
DisplayFirst(5, testLines);
Console.WriteLine();
// Shuffle the previously built strings.
Console.Write("Shuffling strings...");
var randomLines = new List<string>(RandomPermutation(testLines));
Console.WriteLine("done.");
DisplayFirst(5, randomLines);
Console.WriteLine();
return randomLines;
}
/// <summary>
/// Sort the input lines.
/// </summary>
/// <param name="lines">Input lines to sort.</param>
private static void Test(List<string> lines)
{
// Stopwatch to measure time performance
var timer = new Stopwatch();
Console.Write("Sorting " + lines.Count + " lines...");
// Sort benchmark
timer.Start();
lines.Sort();
timer.Stop();
Console.WriteLine("done.");
// Display results
DisplayFirst(5, lines);
Console.WriteLine();
Console.WriteLine((timer.ElapsedMilliseconds / 1000.0).ToString(CultureInfo.InvariantCulture) + " seconds elapsed.");
}
static void Main(string[] args)
{
Console.WriteLine("*** Testing String Sorting in C# ***");
Console.WriteLine();
// Build test lines used for the sort benchmark
List<string> testLines = BuildTestLines();
// Run the sort test
Test(testLines);
}
}
}