Memory is not full released after deleting all QPushButtons in QTApp

asimfile

i am creating a program containing QPushButtons, the Problem is when i am adding QPushButtons memory(RAM) increasing but when i deleted all added buttons memory is not fully releasing.

void TempTest ::addSLOT()
{
  li= new QList<QPushButton*>;
  for(int i=0;i<50000;i++)
   {
     QPushButton *p = new QPushButton;
     p->setText("sample");
     p->setFixedSize(100,100);
     li->append(p);
   }
}
void TempTest ::removeSLOT()
{
  while(li->count())
   {
     QPushButton*p= li->at(0);
     li->removeAt(0);
     delete p;
   }
   delete li;
}

1.initialy memory is 2.0 mb

2.after adding memory increased to 49.3 mb

3.after deleting memory decreased to 4.1 mb

there is 2.1 mb of RAM it never released

BjornW

How do you check memory consumption? Afaik, all memory may not be returned immediately to the OS.

If you run your example multiple times, do you see a steady increase by 2 MB for each iteration?

asimfile

thanks for replying @BjornW
further if i repeat same process -
again add and delete Buttons - 4.4 mb
again add and delete Buttons - 4.9 mb
again add and delete Buttons - 4.6 mb
again add and delete Buttons - 4.4 mb
again add and delete Buttons - 5.4 mb
again add and delete Buttons - 4.9 mb
again add and delete Buttons - 4.6 mb

kshegunov

See my answer here.

asimfile

@kshegunov thanks for reply , i have read your link and it seems OS is resposible for memory loss.

kshegunov

@asimfile said in Memory is not full released after deleting all QPushButtons in QTApp:

it seems OS is resposible for memory loss

You misunderstood. The OS is responsible for memory management. C++ is a stack based language (following ASM's push and pop), everything you allocate on the heap is managed by the OS's heap manager - that's its purpose (small wonder the heap allocation in C is a function). In any case, if you need to make sure you don't leak things, just use a code analyzer.