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PO'List.Contains()' causing 100% CPU usage indefinitely
 

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  1. PO'List.Contains()' causing 100% CPU usage indefinitely
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    <p>While working on a project today I ran into this odd behavior in .NET.</p> <p>I'm grabbing a list of file names and adding them to an object. However I need to filter the incoming names against a known list of "bad" names which led me to do this. (I'm by no means an advanced C# coder, still just learning it.) However, because it causes the <strong>aspnet_wp.exe</strong> process to run at 100% indefinitely, I assume that I'm doing something wrong with the language.</p> <p>Here's my code for reference:</p> <pre><code>List&lt;string&gt; localFiles = new List&lt;string&gt;(); // I was worried the object was causing the issue so dumbed it down to this with no changed. string path = "//&lt;file share&gt;/&lt;dir&gt;/"; // As I commented below yes, it's slow when it works but it's clearly not working when using the if(); List&lt;string&gt; omitNames = new List&lt;string&gt;(); omitNames.Add("Thumbs.db"); // This is the only item in the list when it breaks also. FileInfo[] localFileList = new DirectoryInfo(path).GetFiles(); foreach ( FileInfo item in localFileList ) { if(!omitNames.Contains(item.Name)) { localFiles.Add(path + itemName); } } </code></pre> <p>Can anyone explain why this code runs as an infinite loop? It looks like it really shouldn't. Also, I realize that using a <code>List</code> may not be the best approach. Is there another way to implement this cleanly?</p> <p>Commenting out the <code>if(!){}</code> for <code>omitNames</code> allows the code to run properly. (Though obviously the results are not filtered.)</p> <p><strong>UPDATE:</strong> It was requested to put this in a console app which you'll find below. However it works perfectly. Another thing is that someone suggested that I try to simply compare it against a string. But the exact same thing happens if it's changed to this:</p> <pre><code>if(item.Name != "Thumbs.db") { localFiles.Add(path + itemName); } </code></pre> <p>Console App (which works):</p> <pre><code>using System; using System.IO; using System.Collections.Generic; using System.Linq; using System.Text; namespace LoopKiller { class Program { static void Main(string[] args) { List&lt;string&gt; omitNames = new List&lt;string&gt;(); List&lt;string&gt; localFiles = new List&lt;string&gt;(); omitNames.Add("Thumbs.db"); FileInfo[] localFileList = new DirectoryInfo("c:/test/").GetFiles(); foreach (FileInfo item in localFileList) { if (!omitNames.Contains(item.Name)) { Console.WriteLine("Adding " + item.Name + " to localFiles."); localFiles.Add(item.Name); Console.WriteLine("Item added to localFiles."); } } foreach (string item in localFiles) { Console.WriteLine(item); } Console.ReadLine(); } } } </code></pre>
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    1. USDavidRR
    1. USsiva.k
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    1. COHow many entries are in the directory?
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      1. USOded
    2. COCan you change this into a short but *complete* program (e.g. a console app) which demonstrates the problem?
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      1. USJon Skeet
    3. COWhen you debug, does it add at least one item to the list? Or does it crash immediately?
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      1. USHanlet Escaño
 

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