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POWhy is Array.Sort() so slow compared to LINQ?
 

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  1. POWhy is Array.Sort() so slow compared to LINQ?
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    <p>I made quick testing application to compare LINQ sorting to Array.Sort on my custom objects. Array.Sort seems extremely slow!</p> <p>I made my custom class like this:</p> <pre><code>class Person : IComparable&lt;Person&gt; { public int Age { get; set; } public string Name { get; set; } public int CompareTo(Person obj) { return this.Age.CompareTo(obj.Age); } public Person() { } } </code></pre> <p>Then i made my testing persons in main() :</p> <pre><code>string name = "Mr. Tomek"; Random r = new Random(); int size = 10000000; DateTime start, end; Person[] people1 = new Person[size]; Person[] people2 = new Person[size]; for (int i = 0; i &lt; size; i++) { people1[i] = new Person(); people1[i].Age = r.Next(0, 10000); people1[i].Name = name; people2[i] = new Person(); people2[i].Age = people1[i].Age; people2[i].Name = people1[i].Name; } </code></pre> <p>After that i have measured time taken to Sort by Array.Sort and by LINQ:</p> <pre><code>start = DateTime.Now; var sort = from s in people2 orderby s.Age select s; end = DateTime.Now; Console.WriteLine("LINQ: "); Console.WriteLine((end - start).TotalMilliseconds); start = DateTime.Now; Array.Sort(people1,((Person p1, Person p2)=&gt;{return p1.CompareTo(p2);})); end = DateTime.Now; Console.WriteLine("IComparable: "); Console.WriteLine((end - start).TotalMilliseconds); Console.ReadLine(); </code></pre> <p>Linq time: about 1 or 2 miliseconds</p> <p>Array.Sort: over 16 <strong>SECONDS!</strong></p> <p>All arrays are sorted (LINQ produces new collection and leaves oryginal array unsorted) but Array.Sort is extremely slow! How could it be explained? (in DEBUG and RELEASE mode Array.Sort fails extremely)</p> <p>I pasted code with lambda expression when sorting with Array.Sort but it's the same with and without it. (Class Person implements IComparable interface)</p>
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    1. USTomasz Sikora
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    1. COYou might be interested in my related question. http://stackoverflow.com/questions/10110013/order-of-linq-extension-methods-does-not-affect-performance
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      1. USTim Schmelter
    2. CO@TomaszSikora: You can simply sort by calling `Array.Sort(people1)`, since the `IComparable<T>` implementation is used automatically.
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      1. USOlivier Jacot-Descombes
    3. COI did notice something... Linq is faster when sorting bigger arrays. Array.Sort is faster when Array is less than 100 000 elements. Why is that happening?
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