Unmanaged VC++ Application's memory consumption on windows server

Question

OK, so I have a very large multi-threaded unmanaged c++ application (server) that runs on a windows 2003 server. It hosts sessions for 20-50 concurrent users doing all sorts of business logic... At times it can be using a very large amount of memory due to things like object/session caching due to users having large numbers of windows open in the clients (each window has a separate server 'session'.

We routinely see consumption of more than 5-600 MB physical memory and 5-600 MB of virtual memory. Once it gets to this point we seem to start having 'out of memory' errors.

Now I know that Windows will start page-faulting when it feels it needs to free up physical memory, and also that win32 applications normally are only able to allocate up to a maximum of 4GB worth of memory, really only with 2GB of that available for actual use by the application for 'user-mode' address space, and even less of that after other libraries are loaded... I'm not sure if the 'user-mode' memory usage is what is reported on the Task Manager...

So anyway my real question is:

How can I find out how much user-mode memory my application has access to, and how much has been used at any given time (preferably from outside of the application, i.e. some windows management tool)?

[edit] After looking at the Process Explorer and the website, it looks like the value 'Virtual Size' is the value of how much memory the application has access to.

Answer 1

You wrote:

When your talking how much memory a win32 app can access they specifically call it 'user-mode' memory which I don't see as an option or at least I don't know what column it really is.

Have a look at this article (written by the creator of Process Explorer, Dr. Mark Russinovich).

To be able to manage your Windows systems effectively you need to understand how Windows manages physical resources, such as CPUs and memory, as well as logical resources, such as virtual memory, handles, and window manager objects. Knowing the limits of those resources and how to track their usage enables you to attribute resource usage to the applications that consume them, effectively size a system for a particular workload, and identify applications that leak resources.

Answer 2

I know you asked for preferably from outside of the application, but I was googling for how to find such information from within my own program and stumbled upon your post. So, this is to benefit people who want this information from within their program.

Complete source code included in written in unmanaged C++

#include <windows.h>
#include <stdio.h>
#include <psapi.h>

void PrintMemoryInfo( DWORD processID )
{
    HANDLE hProcess;
    PROCESS_MEMORY_COUNTERS pmc;

    // Print the process identifier.

    printf( "\nProcess ID: %u\n", processID );

    // Print information about the memory usage of the process.

    hProcess = OpenProcess(  PROCESS_QUERY_INFORMATION |
                             PROCESS_VM_READ,
                             FALSE, 
                             processID );
    if (NULL == hProcess)
        return;

    if ( GetProcessMemoryInfo( hProcess, &pmc, sizeof(pmc)) )
    {
        printf( "\tPageFaultCount: 0x%08X\n", pmc.PageFaultCount );
        printf( "\tYour app's PEAK MEMORY CONSUMPTION: 0x%08X\n", 
                  pmc.PeakWorkingSetSize );
        printf( "\tYour app's CURRENT MEMORY CONSUMPTION: 0x%08X\n", pmc.WorkingSetSize );
        printf( "\tQuotaPeakPagedPoolUsage: 0x%08X\n", 
                  pmc.QuotaPeakPagedPoolUsage );
        printf( "\tQuotaPagedPoolUsage: 0x%08X\n", 
                  pmc.QuotaPagedPoolUsage );
        printf( "\tQuotaPeakNonPagedPoolUsage: 0x%08X\n", 
                  pmc.QuotaPeakNonPagedPoolUsage );
        printf( "\tQuotaNonPagedPoolUsage: 0x%08X\n", 
                  pmc.QuotaNonPagedPoolUsage );
        printf( "\tPagefileUsage: 0x%08X\n", pmc.PagefileUsage ); 
        printf( "\tPeakPagefileUsage: 0x%08X\n", 
                  pmc.PeakPagefileUsage );
    }

    CloseHandle( hProcess );
}

int main( )
{
  PrintMemoryInfo( GetCurrentProcessId() );

    return 0;
}