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copied!<p>Okay, I've been following this...I think there are a couple issues, some of which people have touched on, but I think not answering the real question (which, admittedly, took me a while to recognize, and I'm not sure I'm answering what you want even now.)</p> <blockquote> <p>This is all as expected, although what we cannot currently work out is when this memory should be released from the CLR. </p> </blockquote> <p>As others have said, while the task is running, the dictionary will not be released. It's being used. It gets bigger until you run out of memory. I'm pretty sure you understand this.</p> <blockquote> <p>We have let the task complete and then simulated a memory overload situation, but the memory consumed by the dictionary is not released. As the OS is running out of memory, is it not putting pressure on the CLR to release the memory?</p> </blockquote> <p>Here, I think, is the real question. </p> <p>If I understand you correctly, you're saying you set this up to fill up memory. And then, after it crashes (but before you hit return to start a new task) you're trying <em>other things outside of this program, such as running other programs in Windows</em> to try to get the GC to collect the memory, right? Hoping that the OS would talk to the GC, and start pressuring it to do it's thing. </p> <blockquote> <p>However and even more confusing, if we wait until the task has completed, then hit enter to run the task again the memory is released, so obviously the previous dictionary has been garbage collected (hasn't it?).</p> </blockquote> <p>I think you answered your own question...it has not been necessarily been released until you hit return to start a new task. The new task needs memory, so it goes to the GC, and the GC happily collects the memory from the previous task, which has now ended (after throwing from full memory).</p> <blockquote> <p>So, why is the memory not being released? And how can we get the CLR to release the memory? </p> </blockquote> <p>I don't know that you can force the GC to release memory. Generally speaking, it does it when it wants (though some hacker types might know some slick way to force its hand.) Of course, .NET decides when to run the GC, and since nothing is happening while the program is just sitting there, it may well be deciding that it doesn't need to. As to whether the OS can pressure the GC to run, it seems from your tests the answer is "no". A bit counter-intuitive perhaps.</p> <p>Is that what you were trying to get at?</p>

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