.NET EXE memory footprint

Question

Even a simple Notepad application in C# consumes megabytes of RAM as seen in the task manager. On minimizing the application the memory size in the task manager goes down considerably and is back up when the application is maximized.

I read somewhere that the .NET process reserves a lot of memory for runtime allocation in advance. That's why .NET applications have a larger memory footprint to start with. But this memory can be released using Win32 API calls. A trade-off is that runtime allocation becomes slow - is that true?

score 37 · Accepted Answer · edited Aug 16 '11 at 07:55

37

The reason for the large memory footprint is that the JIT compiler and Windows Forms engine are being loaded with your process. To reduce this, you can do the following:

[DllImport("psapi.dll")]
static extern int EmptyWorkingSet(IntPtr hwProc);

static void MinimizeFootprint()
{
    EmptyWorkingSet(Process.GetCurrentProcess().Handle);
}

This should remove as much as possible from your memory footprint. There may be a way that you can also reduce the amount of memory that is set aside for runtime memory allocation.

edited Aug 16 '11 at 07:55

Peter Mortensen

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answered Oct 21 '08 at 20:06

Ed Altorfer

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I'd like to add a note of thanks about this ... I know that working set isn't a valid representation, but that number tends to scare administrators. This tip just took one of my apps in development from an average 80 - 120 meg working set down to 20 - 40. +1 – John Rudy Oct 21 '08 at 20:29
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dotnetcoder--the trade-off is that you will incur a performance hit if your application needs any of the resources you freed, which is relatively likely. – Ed Altorfer Oct 21 '08 at 21:12
John Rudy--I know how that can be; someone sees your app taking "tons of space" and freaks. I'm glad that this helped you a bit. :) – Ed Altorfer Oct 21 '08 at 21:15
I say: Let windows handle the working set size. Forcing it to write everything to the page file is not good for performance. Same reason you should not force garbage collection. Educate people who think, based on the working set size, that your app is taking to much memory. – Lars Truijens Oct 22 '08 at 17:01
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Good idea, just educate the entire world, especially software reviewers. That's a practical solution. Or perhaps not. Seems like it'd be better to take a (probably imperceptible) performance hit. – mhenry1384 May 01 '09 at 18:06
mhenry1384, I think that Lars is saying that it would be helpful for developers to help re-educate their system administrators who think that a working set of 80-120 mb is too large. In many cases, this could be both practical and constructive. – Ed Altorfer May 07 '09 at 23:18

score 29 · Answer 2 · answered Oct 21 '08 at 20:20

TaskManager should not be used to measure the memory footprint of a .NET application.

When a .NET application starts, it asks the OS for a chunk of memory which it then segments to become the managed heap, stack, and large object heap. It is this total chunk of memory that TaskManager is reporting, which may or may not be completely used by .NET. Once a .NET application is given a chunk of memory, it will not release it until asked by the OS, which will only happen with the OS determines a need for more memory resources.

If you want to measure memory allocations, you need to look at the various performance monitor (PerfMon) counters.

You can use interop code to call Win32 APIs to trim your working set size, but the next time your application requests memory from the OS the working set will go back up and there will be a performance hit while the OS allocates and hands out the additional memory and the .NET runtime "configures" it.

score 3 · Answer 3 · answered Oct 21 '08 at 20:06

The task manager does not show real life usage of memory for a .NET app. To see that you almost have to put a performance counter on the app or use a profiler.

What you see in the Task Manager is the working memory of an app which includes a bunch of overhead for the framework itself which must also load when your app loads.

.NET EXE memory footprint

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