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POWhat is the reason behind this huge Performance difference in .Net 4
 

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  1. POWhat is the reason behind this huge Performance difference in .Net 4
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    <p>I was just doing some research on RedBlack Tree. I knew that SortedSet class in .Net 4.0 uses RedBlack tree. So I took that part out as is using Reflector and created a RedBlackTree class. Now I am running some perf test on this RedBlackTree and SortedSet inserting 40000 sequential integral values (starting from 0 to 39999), I am astonished to see that there is huge perf difference as follows:</p> <pre><code> RBTree took 9.27208 sec to insert 40000 values SortedSet took 0.0253097 sec to insert 40000 values </code></pre> <p>What is the reason behind it? BTW I ran the test in Release configuration only and here is the small test code</p> <pre><code> var stopWatch = new Stopwatch(); var rbT = new RedBlackTree&lt;int&gt;(); stopWatch = new Stopwatch(); stopWatch.Start(); for (int i = 0; i &lt; 40000; i++) { rbT.Add(i); } stopWatch.Stop(); Console.WriteLine(stopWatch.Elapsed); var ss = new SortedSet&lt;int&gt;(); stopWatch = new Stopwatch(); stopWatch.Start(); for (int i = 0; i &lt; 40000; i++) { ss.Add(i); } stopWatch.Stop(); Console.WriteLine(stopWatch.Elapsed); </code></pre> <p>Edit</p> <p>I would like to share the code also for RBTree what I've extracted so that you also can run the diagnostics</p> <pre><code>public class Node&lt;T&gt; { public Node(){} public Node(T value) { Item = value; } public Node(T value, bool isRed) { Item = value; IsRed = isRed; } public T Item; public Node&lt;T&gt; Left; public Node&lt;T&gt; Right; public Node&lt;T&gt; Parent; public bool IsRed; } public class RedBlackTree&lt;T&gt; { public RedBlackTree(){} public Node&lt;T&gt; root; int count, version; Comparer&lt;T&gt; comparer = Comparer&lt;T&gt;.Default; public void Add(T item) { if (this.root == null) { this.root = new Node&lt;T&gt;(item, false); this.count = 1; this.version++; return; } Node&lt;T&gt; root = this.root; Node&lt;T&gt; node = null; Node&lt;T&gt; grandParent = null; Node&lt;T&gt; greatGrandParent = null; this.version++; int num = 0; while (root != null) { num = this.comparer.Compare(item, root.Item); if (num == 0) { this.root.IsRed = false; return; } if (Is4Node(root)) { Split4Node(root); if (IsRed(node)) { this.InsertionBalance(root, ref node, grandParent, greatGrandParent); } } greatGrandParent = grandParent; grandParent = node; node = root; root = (num &lt; 0) ? root.Left : root.Right; } Node&lt;T&gt; current = new Node&lt;T&gt;(item); if (num &gt; 0) { node.Right = current; } else { node.Left = current; } if (node.IsRed) { this.InsertionBalance(current, ref node, grandParent, greatGrandParent); } this.root.IsRed = false; this.count++; } private static bool IsRed(Node&lt;T&gt; node) { return ((node != null) &amp;&amp; node.IsRed); } private static bool Is4Node(Node&lt;T&gt; node) { return (IsRed(node.Left) &amp;&amp; IsRed(node.Right)); } private static void Split4Node(Node&lt;T&gt; node) { node.IsRed = true; node.Left.IsRed = false; node.Right.IsRed = false; } private void InsertionBalance(Node&lt;T&gt; current, ref Node&lt;T&gt; parent, Node&lt;T&gt; grandParent, Node&lt;T&gt; greatGrandParent) { Node&lt;T&gt; node; bool flag = grandParent.Right == parent; bool flag2 = parent.Right == current; if (flag == flag2) { node = flag2 ? RotateLeft(grandParent) : RotateRight(grandParent); } else { node = flag2 ? RotateLeftRight(grandParent) : RotateRightLeft(grandParent); parent = greatGrandParent; } grandParent.IsRed = true; node.IsRed = false; ReplaceChildOfNodeOrRoot(greatGrandParent, grandParent, node); } private static Node&lt;T&gt; RotateLeft(Node&lt;T&gt; node) { Node&lt;T&gt; right = node.Right; node.Right = right.Left; right.Left = node; return right; } private static Node&lt;T&gt; RotateRight(Node&lt;T&gt; node) { Node&lt;T&gt; left = node.Left; node.Left = left.Right; left.Right = node; return left; } private static Node&lt;T&gt; RotateLeftRight(Node&lt;T&gt; node) { Node&lt;T&gt; left = node.Left; Node&lt;T&gt; right = left.Right; node.Left = right.Right; right.Right = node; left.Right = right.Left; right.Left = left; return right; } private static Node&lt;T&gt; RotateRightLeft(Node&lt;T&gt; node) { Node&lt;T&gt; right = node.Right; Node&lt;T&gt; left = right.Left; node.Right = left.Left; left.Left = node; right.Left = left.Right; left.Right = right; return left; } private void ReplaceChildOfNodeOrRoot(Node&lt;T&gt; parent, Node&lt;T&gt; child, Node&lt;T&gt; newChild) { if (parent != null) { if (parent.Left == child) { parent.Left = newChild; } else { parent.Right = newChild; } } else { this.root = newChild; } } } </code></pre> <hr> <p>Edit</p> <hr> <p>I ran the same diagnostic on some other data structure (some created by me*, some from .net framework**) and here is the interesting results</p> <pre><code>*AATree 00:00:00.0309294 *AVLTree 00:00:00.0129743 **SortedDictionary 00:00:00.0313571 *RBTree 00:00:09.2414156 **SortedSet 00:00:00.0241973 </code></pre> <p>RBTree is the same as above (stripped out from SortedSet class). <strong>I tried with 400000 values also, but RBTree seems taking FOREVER</strong>, I really don't know why.</p>
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    2. COHave you tried using a profiler to find out where your code spends the most time at?
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    3. COWhen you say you "ran" the test in Release configuration - was that inside the debugger? or at a flat command prompt?
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