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    <p>I don't actually know the answer, but feel it's important to point out that <code>lock</code> and <code>Monitor.TryEnter</code> are <strong>not</strong> functionally equivalent. From <a href="http://msdn.microsoft.com/en-us/library/4tssbxcw.aspx" rel="noreferrer">the MSDN documentation on <code>Monitor.TryEnter</code></a>:</p> <blockquote> <p>If successful, this method acquires an exclusive lock on the obj parameter. This method returns immediately, whether or not the lock is available.</p> </blockquote> <p>The <code>lock</code> statement is analogous to <code>Monitor.Enter</code>, which <em>does</em> potentially block. Granted, in your example code, there shouldn't be any blocking issues; but I would wager that since <code>lock</code> provides blocking, it does a little more work (potentially) than <code>TryEnter</code> does.</p> <hr> <p>For what it's worth, I just tried your code on my machine and got <strong>completely</strong> different results:</p> <p>100 iterations:<br> <code>lock</code>: 4.4 microseconds<br> <code>Monitor.TryEnter</code>: 16.1 microseconds<br> <code>Monitor.Enter</code>: 3.9 microseconds</p> <p>100000 iterations:<br> <code>lock</code>: 2872.5 microseconds<br> <code>Monitor.TryEnter</code>: 5226.6 microseconds<br> <code>Monitor.Enter</code>: 2432.9 microseconds</p> <p>This seriously undermines my initial guess and shows that, on my system, <code>lock</code> (which performs about the same as <code>Monitor.Enter</code>) actually drastically <em>outperforms</em> <code>Monitor.TryEnter</code>.</p> <hr> <p>Indeed, I attempted this in VS 2010 targeting both .NET 3.5 and .NET 4.0 and, though the results were different, in each case <code>lock</code> did in fact outperform <code>Monitor.TryEnter</code>:</p> <h2>Runtime version: 2.0.50727.3603</h2> <p>Ran 100 times, 100000 iterations each time:<br> <strong>Lock: 279736.4</strong> microseconds<br> <strong>Monitor.TryEnter: 1366751.5</strong> microseconds<br> Monitor.TryEnter (no timeout): 475107.3 microseconds<br> Monitor.Enter: 332334.1 microseconds</p> <h2>Runtime version: 4.0.30128.1</h2> <p>Ran 100 times, 100000 iterations each time:<br> <strong>Lock: 334273.7</strong> microseconds<br> <strong>Monitor.TryEnter: 1671363.4</strong> microseconds<br> Monitor.TryEnter (no timeout): 531451.8 microseconds<br> Monitor.Enter: 316693.1 microseconds</p> <p>(Notice I also tested <code>Monitor.TryEnter</code> with no timeout, as I agreed with Marc that calling <code>TimeSpan.FromSeconds</code> was almost certainly slowing down your times for <code>Monitor.TryEnter</code>--and these tests support that--though it's strange, since in <em>your</em> case apparently <code>lock</code> is <em>still</em> significantly slower.)</p> <p>Based on these results I am strongly inclined to believe that your measured execution times are somehow affected by running this code with the <code>Test</code> attribute. Either that or this code is far more machine-dependent than I would have expected.</p>
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    1. COit was my initial assumption. but it is wrong. TryEnter is even slower than lock or Enter
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    2. CO@Andrey: That was my finding as well, it turns out. Strange that our results would be so different from the OP's.
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