Re: Memory deallocation does not work.

From:
"Grizlyk" <grizlyk1@yandex.ru>
Newsgroups:
comp.lang.c++
Date:
Tue, 13 Feb 2007 02:03:07 +0300
Message-ID:
<eqqrpd$or9$1@aioe.org>
christophe.chazeau@gmail.com wrote:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <vector>
#include <iterator>

using namespace std;

class Test{
public :
 unsigned char *data ;

 Test(){

 }
 void Go(int taille)
 {

   data = (unsigned char*) malloc(taille);
   printf("malloc : %p\n",data);
 }

 ~Test()
 {
   printf("delete %p\n",data);
   free(data);
 }

};

vector<Test *> v;


It is dangerous - possible memory leak because vector<Test *> does not own
the object pointer point to. Use any RAII memory wrapper (see RAII here:
http://www.hackcraft.net/raii ) instead of Test *

vector<auto_ptr<Test> > v;

or give each address (stored in vector<Test *>) to other object, which will
keep object.

{
auto_ptr<Test> owner(new Test);
vector<Test *> v;
    v.push_back(*owner);
}

int i = 0 ;

int main()
{

 sleep(10);

 for(i = 0;i<10000;i++)
   {
     Test *t = new Test();
     t->Go(75000);
     v.push_back(t);
   }

 sleep(10);

 vector<Test *>::iterator it;
 for(it=v.begin() ; it!=v.end();it++)


Do you need "it" outside of "for"?
Try to inplement postfix operator ++, and you will see, that pferix ++ is
better.
Avoid repeating function call "v.end()" if you are sure, that the function
will always return the same.

 vector<Test *>::iterator end(v.end());
 for(vector<Test *>::iterator it(v.begin()); it!=end; ++it)

   {

     Test *t = *it;
     delete(t);
   }
 sleep(10);

}


To return memory to OS, instead of std malloc/free you need to implement
native for you OS memory manager

namespace Nxxx_OS
{
void* malloc(); //will call OS specific allocate
void free(void*const); //will call OS specific free

//namespace Nxxx_OS
}

Note, you need to stay coherrent with all other memory management, so
probably you need to change all system memory allocation for the target.

--
Maksim A. Polyanin

"In thi world of fairy tales rolls are liked olso"
                               /Gnume/

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