memory leak

[mattia]

If you want to delete an object you no longer use, you have to do that before it goes out of scope, because you won't be able to reach it later.

In this case you don't have to delete the object that tempQTreeWidgeItem points to, because you add it to thetwmTreeWidget, which is responsible for deleting it.

Thanks so much for the explanetion.
Get back at my memory leak cos i'm not able to understand where i'm getting wrong.
This is a little piece of valgrind command report:

==16797== 2848 (16 direct, 2832 indirect) bytes in 4 blocks are definitely lost in loss record 75 of 144
==16797==    at 0x1B90939A: operator new(unsigned) (vg_replace_malloc.c:132)
==16797==    by 0x818DE38: twmConfigObject::getPoolIconTooltip(int, QString) (twmConfig.cpp:4968)
==16797==    by 0x81ADCB9: twmConfigObject::setupPoolsGetTreeView(QTreeWidget*, bool) (twmConfig.cpp:1210)
==16797==    by 0x80BA4D0: twmMainWindow::setupPools(bool) (twmMainWindow.cpp:1387)
==16797==    by 0x812DE02: twmMainWindow::twmMainWindow(QWidget*) (twmMainWindow.cpp:54)
==16797==    by 0x80A0317: main (trm.cpp:62)

==16797== 2848 (16 direct, 2832 indirect) bytes in 4 blocks are definitely lost in loss record 75 of 144
==16797==    at 0x1B90939A: operator new(unsigned) (vg_replace_malloc.c:132)
==16797==    by 0x818DE38: twmConfigObject::getPoolIconTooltip(int, QString) (twmConfig.cpp:4968)
==16797==    by 0x81ADCB9: twmConfigObject::setupPoolsGetTreeView(QTreeWidget*, bool) (twmConfig.cpp:1210)
==16797==    by 0x80BA4D0: twmMainWindow::setupPools(bool) (twmMainWindow.cpp:1387)
==16797==    by 0x812DE02: twmMainWindow::twmMainWindow(QWidget*) (twmMainWindow.cpp:54)
==16797==    by 0x80A0317: main (trm.cpp:62)

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I think that the problem is in my twmConfigObject::getPoolIconTooltip(int, QString) method, and down here the method's code:

QString twmConfigObject::getPoolIconTooltip ( int theStatus , QString poolName )
{
	QString difference;
	countNotSync( TWMACTUALMODE__POOLS  , false , & difference );
 
	switch ( theStatus )
	{
		case POOLSTATUS__UNDEF:
 
			if ( ! difference.isEmpty() && difference != 0)
			{
				return ( QString ( tr ( "Pool %1 status is: Undefined - %2 difference" ).arg ( poolName ).arg ( difference ) ) );
			}
			else
			{
				return ( QString ( tr ( "Pool %1 status is: Undefined" ).arg ( poolName ) ) );
			}
			break;
 
		case POOLSTATUS__INCOMPLETESHARE:
 
			if ( ! difference.isEmpty() && difference != 0)
			{
				return ( QString ( tr ( "Pool %1 status is: Incomplete share - %2 difference" ).arg ( poolName ).arg ( difference ) ) );
			}
			else
			{
				return ( QString ( tr ( "Pool %1 status is: Incomplete share" ).arg (poolName) ) );
			}
			break;
 
		case POOLSTATUS__SHARED:
 
			if ( ! difference.isEmpty() && difference != 0)
			{
				return ( QString ( tr ( "Pool %1 status is: Shared - %2 difference" ).arg ( poolName ).arg ( difference ) ) );
			}
			else
			{
				return ( QString ( tr ( "Pool %1 status is: Shared" ).arg (poolName) ) );
			}
			break;
 
		default:
 
			return ( QString ( tr ( "Terminal %1 status is: Undefined" ).arg (poolName) ) );
			break;
	}
}

QString twmConfigObject::getPoolIconTooltip ( int theStatus , QString poolName )
{
	QString difference;
	countNotSync( TWMACTUALMODE__POOLS  , false , & difference );
	
	switch ( theStatus )
	{
		case POOLSTATUS__UNDEF:
			
			if ( ! difference.isEmpty() && difference != 0)
			{
				return ( QString ( tr ( "Pool %1 status is: Undefined - %2 difference" ).arg ( poolName ).arg ( difference ) ) );
			}
			else
			{
				return ( QString ( tr ( "Pool %1 status is: Undefined" ).arg ( poolName ) ) );
			}
			break;
			
		case POOLSTATUS__INCOMPLETESHARE:
			
			if ( ! difference.isEmpty() && difference != 0)
			{
				return ( QString ( tr ( "Pool %1 status is: Incomplete share - %2 difference" ).arg ( poolName ).arg ( difference ) ) );
			}
			else
			{
				return ( QString ( tr ( "Pool %1 status is: Incomplete share" ).arg (poolName) ) );
			}
			break;
			
		case POOLSTATUS__SHARED:
			
			if ( ! difference.isEmpty() && difference != 0)
			{
				return ( QString ( tr ( "Pool %1 status is: Shared - %2 difference" ).arg ( poolName ).arg ( difference ) ) );
			}
			else
			{
				return ( QString ( tr ( "Pool %1 status is: Shared" ).arg (poolName) ) );
			}
			break;
			
		default:
			
			return ( QString ( tr ( "Terminal %1 status is: Undefined" ).arg (poolName) ) );
			break;
	}
}

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any hint?

[jacek]

Is new operator used in countNotSync()?

[mattia]

No, i don't use any new operator in that function, but i call some other functions and there are not new statement into them.

[jacek]

Does the leak disappear, if you comment out all of the code and add "return QString();" instead?

[mattia]

i have a trouble to read the leak summary...

#
==3325==    definitely lost: 708 bytes in 77 blocks.
#
==3325==    indirectly lost: 22729 bytes in 420 blocks.
#
==3325==      possibly lost: 0 bytes in 0 blocks.
#
==3325==    still reachable: 728510 bytes in 26553 blocks.  <-- have i lost them(728510bytes)?

#
==3325==    definitely lost: 708 bytes in 77 blocks.
#
==3325==    indirectly lost: 22729 bytes in 420 blocks.
#
==3325==      possibly lost: 0 bytes in 0 blocks.
#
==3325==    still reachable: 728510 bytes in 26553 blocks.  <-- have i lost them(728510bytes)?

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[jacek]

have i lost them(728510bytes)?

No, there's still some way to reach that data. For example Qt might store pointers somewhere inside itself.

Whether that's a leak or not depends on whether this amount rises with time or not. For example if you have a loop where you create temporary QObjects, give them a parent and forget to delete them. You will get a leak, but the data is "reachable" all the time through the parent. On other hand you might create a single array using new operator and as long as there's only one such array you don't have a leak, even if you never free the memory it occupies.