I have added FastMM4 to my project for detect a memory leak
program MyProg;
uses
{$IFDEF DEBUG}
FastMM4,
{$ENDIF}
...other uses
on form close FastMM4 produce a MemoryManager_EventLog.txt, with all leak block.
This is an example:
--------------------------------2019/6/19 9:49:25--------------------------------
A memory block has been leaked. The size is: 20
This block was allocated by thread 0x558, and the stack trace (return addresses) at the time was:
4075D2 [System.pas][System][@GetMem$qqri][4614]
40ABAF [System.pas][System][TObject.NewInstance$qqrv][16452]
40B3D6 [System.pas][System][@ClassCreate$qqrpvzc][17790]
40AD20 [System.pas][System][TObject.$bctr$qqrv][16516]
F3BEF6 [NdST.pas][NdST][TFinder.$bctr$qqrp14System.TObject][1011]
11157D1 [SuperNode.pas][SuperNode][TSuperNode.$bctr$qqrp14System.TObject][993]
D1D840 [Network.pas][Network][TNetwork.Create$qqrv][968]
F3A70D [NdST.pas][NdST][TNdST.$bctr$qqrp14System.TObject][177]
F3B658 [NdST.pas][NdST][TNdSTCAP.$bctr$qqrp14System.TObject][652]
10A4CCA [Print.pas][Print][TPrint.CreateCollection$qqrv][4274]
10A2773 [Print.pas][Print][TPrint.CreateItem$qqrv][3031]
The block is currently used for an object of class: TList
The allocation number is: 53883
Current memory dump of 256 bytes starting at pointer address 7EBA5360:
48 FA 49 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 7C C4 2D 79 00 00 00 00 E0 4B BA 7E
00 00 00 00 00 00 00 00 9C CD 41 00 00 00 00 00 7C D2 00 00 D2 75 40 00 AF AB 40 00 D6 B3 40 00
1A 72 11 01 29 AD 40 00 F8 57 11 01 40 D8 D1 00 0D A7 F3 00 58 B6 F3 00 CA 4C 0A 01 73 27 0A 01
58 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
20 AD 40 00 B8 AB 40 00 D1 57 11 01 F4 1B 0B 01 22 4D 0A 01 87 27 0A 01 0A 48 11 01 52 6E 11 01
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The leak seem to be caused by TList, but I free every TList. Is TList.Free not sufficient?
If you create objects and save their references to TList, it is essential that you free them before the TList is freed.
for I := 0 to aList.Count-1 do
anObjectType(aList[I]).Free;
If you want your objects to be freed automatically, use TObjectList with OwnsObjects parameter set. TObjectList frees the memory of all its objects when it is destroyed.