Question

I been working in a project, but recently I check if my program has some leaking and the results is that it’s leaking and a lot.

I use _CrtDumpMemoryLeaks(); to receive all the messages of leaking and I check that most of them are related with boost, I know that it must be my problem, but I can’t understand why it’s leaking.

In the debug output shows me these lines:

Dumping objects ->
{673} normal block at 0x00E075E0, 8 bytes long.
 Data: <H   @e  > 48 92 E0 00 40 65 E0 00 
{671} normal block at 0x00E065C0, 8 bytes long.
 Data: <@e      > 40 65 E0 00 00 00 00 00 
{669} normal block at 0x00E06540, 68 bytes long.
 Data: < e  mountains.pn> C0 65 E0 00 6D 6F 75 6E 74 61 69 6E 73 2E 70 6E 
{665} normal block at 0x00E063B0, 8 bytes long.
 Data: <H       > 48 92 E0 00 00 00 00 00 
{663} normal block at 0x00E09248, 68 bytes long.
 Data: < c  nubes.png   > B0 63 E0 00 6E 75 62 65 73 2E 70 6E 67 00 CD CD 

Which leads me to believe that the problem is where I use those strings, and the first call with those are in these lines:

tutorialLevel->addLayerToList("nubes.png", 1600.f, 720.f, 1.0f, 0.0f, 0.1f, true);
tutorialLevel->addLayerToList("mountains.png", 1600.f, 720.f, speedXVectorPanda.at(0), 0.0f, 0.5f, false);

And the actual function addLayerToList is the next:

void Level::addLayerToList(std::string name, GLfloat widthLayer, GLfloat heightLayer, GLfloat velX, GLfloat velY, 
                GLfloat constantX, bool hasRepetition)
{
    layersList.push_back( new Layer(name, widthLayer, heightLayer, velX, velY, constantX, hasRepetition) );
}

And layersList is define like this:

boost::ptr_vector< Layer > layersList;

Maybe, I misunderstood how the ownership of pointers work in Boost, but in the examples I recently check, this is a correct way to pass ownership of the object to the ptr_vector, am I wrong?

And my other question is, if it’s necessary release the pointers for the vector, or it’s better leave the auto_ptr do his work?

Thanks for the help.

Answer 1

Depending on where you placed it but in almost all cases, _CrtDumpMemoryLeaks will not show you the truth when using STL/BOOST smart pointers. It will see the usage of new within the STL as a memory leak.