Collection

Your answer was very professional. However, since you declared that you are "not too familiar with the MFC containers", I decided to do a test of my own. Although this test is not definitive, it appears that managed code significantly outperforms both STL and MFC, both in terms of memory usage and of speed! I have to admit I am very surprised by this result.

I created the following lists (this type of collection is declared to be the best performing on all systems)

STL: list<MyClass*> STL_list
MFC: CPtrList MFC_list
Managed: List<MyRefClass^> CLR_list

I let each list grow by 100,000 elements (each element is a pointer to MyClass / handle to MyRefClass respectively), then a search through the list, finally I destroy all the elements and the list. Here are the results.

	STL	MFC	Managed	End
INITIAL
Paged=Private	10,825,728	11,038,720	11,091,968	13,856,768
WorkingSet	9,117,696	9,539,584	9,625,600	12,365,824
FULL LIST
Paged=Private	14,913,536	13,950,976	13,791,232
WorkingSet	13,336,576	12,480,512	12,259,328
delta Paged	4,087,808	2,912,256	2,699,264
delta WorkingSet	4,218,880	2,940,928	2,633,728
ELAPSED TIME	0.1044688	0.0670864	0.0102848

I do not understand why apparently memory is not recovered after destroying CLR_list (see coloumn 'End'), however the results seem impressive expecially for the elapsed time.

Just for your information and for completeness.

Regards. Following is the complete source:

// TestList.cpp : Defines the entry point for the console application.

//

#include"stdafx.h"

#include"TestList.h"

#define RAND_ITEMS 100000

// The one and only application object

usingnamespace std;

usingnamespace System;

usingnamespace System::Diagnostics;

usingnamespace System::Collections::Generic;

class MyClass {

public:

int x,y;

MyClass(int xx,int yy) : x(xx),y(yy) {}

};

refclass MyRefClass {

public:

int x,y;

MyRefClass(int xx,int yy) : x(xx),y(yy) {}

//~MyRefClass() { Console::WriteLine("Destroying {0}",x); }

//!MyRefClass() { Console::WriteLine("Finalizing {0}",x); }

void DisplayMemory(String^ str)

{

Process^ proc = Process::GetCurrentProcess();

Console::WriteLine("Memory - {0}:",str);

Console::WriteLine("Paged=Private {0}",proc->PrivateMemorySize64);

Console::WriteLine("WorkingSet {0}",proc->WorkingSet64);

}

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])

{

int nRetCode = 0;

// initialize MFC and print and error on failure

if (!AfxWinInit(::GetModuleHandle(NULL), NULL, ::GetCommandLine(), 0))

{

// TODO: change error code to suit your needs

_tprintf(_T("Fatal Error: MFC initialization failed\n"));

nRetCode = 1;

}

else

int i,count,r[RAND_ITEMS];

MyClass* p;

// declare the lists

// initialize r[]

for(i=0 ; i<RAND_ITEMS ; i++)

{

UINT u;

if(0!=rand_s(&u))

{

Console::WriteLine("The rand_s function failed");

return 2;

}

r = (int)((double)u/(double)UINT_MAX*1000);

}

// Perfomance test

// STL

Console::WriteLine("Testing STL");

DisplayMemory("Initial");

sw.Start();

for(i=0 ; i<RAND_ITEMS ; i++) STL_list.push_back(new MyClass(i,r));

DisplayMemory("Full List");

count = 0;

foreach(p in STL_list) if(p && p->y==500) count++;

Console::WriteLine("Count = {0}",count);

while(!STL_list.empty())

{

p = (MyClass*)STL_list.back();

if(p) delete p;

STL_list.pop_back();

}

sw.Stop();

Console::WriteLine("Elpsed time: {0}",sw.Elapsed);

sw.Reset();

// MFC

Console::WriteLine("\nTesting MFC");

DisplayMemory("Initial");

sw.Start();

for(i=0 ; i<RAND_ITEMS ; i++) MFC_list.AddTail(new MyClass(i,r));

DisplayMemory("Full List");

count = 0;

POSITION pos = MFC_list.GetHeadPosition();

while(pos)

{

p = (MyClass*)MFC_list.GetNext(pos);

if(p && p->y==500) count++;

}

Console::WriteLine("Count = {0}",count);

while(!MFC_list.IsEmpty())

{

p = (MyClass*)MFC_list.GetTail();

if(p) delete p;

MFC_list.RemoveTail();

}

sw.Stop();

Console::WriteLine("Elpsed time: {0}",sw.Elapsed);

sw.Reset();

// Managed

Console::WriteLine("\nTesting CLR");

DisplayMemory("Initial");

sw.Start();

for(i=0 ; i<RAND_ITEMS ; i++) CLR_list.Add(gcnew MyRefClass(i,r));

DisplayMemory("Full List");

count = 0;

foreach(MyRefClass^ p in CLR_list) if(p && p->y==500) count++;

Console::WriteLine("Count = {0}",count);

foreach(MyRefClass^ p in CLR_list) if(p) delete p;

CLR_list.Clear();

CLR_list.TrimExcess();

sw.Stop();

Console::WriteLine("Elpsed time: {0}",sw.Elapsed);

// End

DisplayMemory("End");

}

return nRetCode;

}

giorgiosf at 2007-10-8 >