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C++ Visual Studio 2010 Memory Leak Tracking


Question

I am writing a game in C++ using SDL as the main library, and everything seems to be going okay. However I am noticing large memory usage when I load in a texture, and freeing up pointers/objects with delete() doesn't seem to be actually freeing up memory. So on linux I used ValGrind but I find it difficult to understand where my problems are happening.

I copied my code over and have it compiling and running under Windows using Visual Studio 2010 Pro. I notice the memory usage is the same on both windows and linux, and the memory use doesn't rise constantly but it does rise when objects are created (normal), however before creation is should be deleting the one previously taking that memory space (not freeing), and using some couts I can see that it is freeing them.

ie)

MyObject *obj = new MyObject() // results in + 200kb used

delete(obj) // Doesn't reduce memory by 200kb

obj = NULL // Just sets the pointer to null

If I kept running that my memory would constantly grow by 200kb (which I think is far more than that object should be using anyways). So to try and figure out what was going on I tried adding in the leak code as stated by MS on MSDN.

http://msdn.microsoft.com/en-us/library/e5ewb1h3(v=vs.80).aspx

I put that in my main.cpp file and put the "_CrtDumpMemoryLeaks();" in my main function which looks like


int main(int argc,char[] argv)
{
_putenv("SDL_CENTER_WINDOW");
AttikClient::StartGame();
_CrtDumpMemoryLeaks();
return 0;
}
[/CODE]

AttikClient::StartGame() initializes a static function in a static class, that has the main game loop and other logic. However when I close my program there is no leak output in the output window. I have debug on as I can step through the code and can see basic output but no leak information.

I have also tried VLD (Visual Leak Detector) http://www.codeproject.com/Articles/9815/Visual-Leak-Detector-Enhanced-Memory-Leak-Detectio

And got the same results. The build mode is for sure set as debug, and I make sure to do F5 which is Debug Application. Am I missing something?

8 answers to this question

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I'm no programmer, but a quick search on google returned this: http://stackoverflow.com/questions/2153776/how-to-use-crtdumpmemoryleaks

It says you need to tell the software where to display messages. And since you're software already says "return 0;" I'm guessing you won't even get the "1" value for leaks, and "0" for no leaks.

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I found the problem kindof.

I needed to set the Runtime Environment to be /MDd instead of /MD which will enable _DEBUG. Now I can see some memory leaks, however I copied the code from MS and I still don't see a file name for where the leak occured. I defined everything that it says to.

Also, now when I try the VLD I just get an Application Failed To Start crash.

Okay. This thread can be closed, I found the issue with VLD (was missing 2 files). All seems to be working :D

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  On 29/05/2013 at 16:54, Asik said:

There's your memory leak :laugh:

Was originally going to do it in XNA/C# however I wanted to make it cross platform without having to do major re-writes. At this point the only changes to go from linux to windows is a third part pthread class, and a couple different libs for networking.

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  On 29/05/2013 at 17:34, firey said:

Was originally going to do it in XNA/C# however I wanted to make it cross platform without having to do major re-writes. At this point the only changes to go from linux to windows is a third part pthread class, and a couple different libs for networking.

Have you considered MonoGame? If anything you should have even less code differences between platforms going .NET/MonoGame than C++/SDL. No need for different libraries for threading and networking, for instance, as that's standard in .NET.
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  On 29/05/2013 at 17:38, Asik said:

Have you considered MonoGame? If anything you should have even less code differences between platforms going .NET/MonoGame than C++/SDL. No need for different libraries for threading and networking, for instance, as that's standard in .NET.

I had considered it. However the C++ also serves the dual purpose of teaching me C++. I am proficient in C#/VB/PHP so I figure I might as well learn C++ syntax as well.

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