How to find the root cause of memory leak?-CodePudding

Sometime, when I close my app I have this error :

---------------------------
Unexpected Memory Leak
---------------------------
An unexpected memory leak has occurred. The unexpected small block leaks are:
    
21 - 28 bytes: TGradientPoints x 2, TGradientPoint x 4, Unknown x 2
29 - 36 bytes: TD2DBitmapHandle x 1, TGradient x 2, TBitmapImage x 3, TBrushBitmap x 2
37 - 44 bytes: TFont x 1, TList<System.Classes.TCollectionItem> x 2, TBrushResource x 2, TPosition x 12
45 - 52 bytes: TBitmap x 3, TObjectList<FMX.Graphics.TCanvasSaveState> x 1, UnicodeString x 1
53 - 60 bytes: TBrush x 1
61 - 68 bytes: Unknown x 1
69 - 76 bytes: TTransform x 2
77 - 84 bytes: TStrokeBrush x 1
237 - 252 bytes: TCanvasD2D x 1
    
---------------------------
OK   
---------------------------

The problem is that I can't find out from where those memory leaks come from and as this exception raise very rarely it's very hard to debug. :(

Is their any good way to find the root cause of memory leak?

CodePudding user response：

The only solution is to identify the classes where you create object instances and find and/or debug the point in code where you should deallocate them.

I don't have you code under my hands, but I could deduce from your leaks report that TFont, TBrush and TBitmap may belong to a TForm instantied by hand (and not by Application.CreateForm) in your code and not freed.

The latter one should be a good starting point...

CodePudding user response：

The option is to use FASTMM5 instead of the default FastMM4 included in Delphi. with FastMM5 we can do :

  if FastMM_LoadDebugSupportLibrary then
  begin
    FastMM_EnterDebugMode;
    FastMM_MessageBoxEvents := FastMM_MessageBoxEvents   [mmetUnexpectedMemoryLeakDetail];
  end;

Then at shunt down we have the exact stack trace of the memory leak.