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POGarbage collector test
 

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    <p>I have written a simple .net forms application to test some behaviour of .NET about how it handles memory together with the garbage collector to do the cleaning.</p> <p>The forms application GUI looks like this:</p> <p><img src="https://i.stack.imgur.com/K1aTI.png" alt="Application GUI"></p> <p>And the code behind like this:</p> <pre><code>public partial class Form1 : Form { private readonly IList&lt;byte[]&gt; _btyList = new List&lt;byte[]&gt;(); public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { int i = 0; while (i &lt; 3) { byte[] buffer = File.ReadAllBytes(@"C:\PFiles\20131018_nl_metro holland.pdf"); _btyList.Add(buffer); i++; } } private void button2_Click(object sender, EventArgs e) { int i = 0; while (i &lt; _btyList.Count) { _btyList[i] = null; i++; } } private void button3_Click(object sender, EventArgs e) { GC.Collect(); } } </code></pre> <p>When I add a couple of byte arrays to the private list of byte arrays it (of course) has effect on the memory usage of the application:</p> <p><img src="https://i.stack.imgur.com/ASY1P.png" alt="Memory usage after adding byte arrays"></p> <p>Now when I press the Clear memory button the memory usage will stay the same. I can wait for hours, but it doesn't change. If I press the Garbage collect button (after Clear memory) it will free the memory immediately:</p> <p><img src="https://i.stack.imgur.com/kFbiJ.png" alt="Memory usage after garbage collect"></p> <p>The question is: Why does the garbage collector not work in this case?</p>
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    1. USKees de Wit
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    1. COIt isn't running because it doesn't need to. If memory is not low, there is no need to collect.
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    2. COIt needs to run, because 360MB of memory is in use for nothing.
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    3. CO"It needs to run, " - says who? If you have 4GB of memory. 360MB is probably below the collection threshold. Just because you assume it works a particular way does not make it true. You shouldn't, in general, ever worry or think about when the GC runs, unless you are writing critical code.
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