ToListTest.cs

/*--------------------------------------------------------------------------------------------
 * Copyright (c) 2019 Celso Junior, All rights reserved.
 * Licence: Copy 'n paste freed! \o/
 * Description: Csharp program benchmarking the best place to use .ToList() method
 * --------------------------------------------------------------------------------------------*/
 
using System;
using System.Linq;
using System.Collections.Generic;
					
public class Program
{
	const int length = 100000;
	
	public static void Main()
	{
		Primeiro();
		Segundo();
	}
	
	public static void Primeiro()
	{
		var before2 = GC.CollectionCount(2);
		var before1 = GC.CollectionCount(1);
		var before0 = GC.CollectionCount(0);
		
		var startTime = DateTime.Now;
		
		var bar = default(IEnumerable<int>);
		for (int i = 0; i < length; i++)
		{
			var foo = default(IEnumerable<int>);
			foo = Enumerable.Range(0, 1000);
			bar = foo.ToList().Skip(500).Take(10);
		}
		
		Console.WriteLine($"Resultado : {bar.Count()}");
		
		Console.WriteLine(@$"Tempo total: {DateTime.Now.Subtract(startTime):hh\:mm\:ss\:fff}");
		Console.WriteLine($"GC Gen #2 : {GC.CollectionCount(2) - before2} coletas");
		Console.WriteLine($"GC Gen #1 : {GC.CollectionCount(1) - before1} coletas");
		Console.WriteLine($"GC Gen #0 : {GC.CollectionCount(0) - before0} coletas\n");
	}
	
	public static void Segundo()
	{
		var before2 = GC.CollectionCount(2);
		var before1 = GC.CollectionCount(1);
		var before0 = GC.CollectionCount(0);
		
		var startTime = DateTime.Now;
		
		var bar = Enumerable.Empty<int>();
		for (int i = 0; i < length; i++)
		{
			var foo = Enumerable.Empty<int>();
			foo = Enumerable.Range(0, 1000);
			bar = foo.Skip(500).Take(10).ToList();
		}
		
		Console.WriteLine($"Resultado : {bar.Count()}");
		
		Console.WriteLine(@$"Tempo total: {DateTime.Now.Subtract(startTime):hh\:mm\:ss\:fff}");
		Console.WriteLine($"GC Gen #2 : {GC.CollectionCount(2) - before2} coletas");
		Console.WriteLine($"GC Gen #1 : {GC.CollectionCount(1) - before1} coletas");
		Console.WriteLine($"GC Gen #0 : {GC.CollectionCount(0) - before0} coletas\n");
	}
}

/* output
Resultado : 10
Tempo total: 00:00:00:720
GC Gen #2 : 0 coletas
GC Gen #1 : 1 coletas
GC Gen #0 : 40 coletas

Resultado : 10
Tempo total: 00:00:00:021
GC Gen #2 : 0 coletas
GC Gen #1 : 0 coletas
GC Gen #0 : 2 coletas
*/