DCEF memory leak in Delphi XE2

Question

I have installed the following version of DCEF3 https://github.com/hgourvest/dcef3

I start a new VCL application and drop the Chromium component. If I run this application I have no errors but if I add the following line:

procedure TForm2.Button3Click(Sender: TObject);
begin
  Chromium1.Load('http://www.google.com');
end;

I have two memory leaks when I close the application.

I tried to move the Chromium1.Load part in another part of the application but the memory leak is still there

The following is the memory dump from MadExcept

allocation number: 1990
program up time: 529 ms
type: GetMem
address: $845afb0
size: 80
access rights: read/write

main thread ($cb0):
671cd312 madExcept32.dll madExceptDbg    1603 GetMemCallback
00404538 MyBrowser.exe   System           290 @GetMem
0059ad91 MyBrowser.exe   ceflib         12986 TCefBaseOwn.CreateData
0059e880 MyBrowser.exe   ceflib         15920 TCefClientOwn.Create
005ab4cc MyBrowser.exe   cefgui           648 TCustomClientHandler.Create
005aff37 MyBrowser.exe   cefvcl           798 TVCLClientHandler.Create
005b03b2 MyBrowser.exe   cefvcl           891 TCustomChromium.GetClientHandler
005b009f MyBrowser.exe   cefvcl           830 TCustomChromium.Create
00478fa5 MyBrowser.exe   System.Classes       CreateComponent
004791d0 MyBrowser.exe   System.Classes       TReader.ReadComponent
00479481 MyBrowser.exe   System.Classes       TReader.ReadDataInner
004793c0 MyBrowser.exe   System.Classes       TReader.ReadData
0047f91d MyBrowser.exe   System.Classes       TComponent.ReadState
004f7aa3 MyBrowser.exe   Vcl.Controls         TControl.ReadState
004fc0bd MyBrowser.exe   Vcl.Controls         TWinControl.ReadState
00573bb9 MyBrowser.exe   Vcl.Forms            TCustomForm.ReadState
0047a343 MyBrowser.exe   System.Classes       TReader.ReadRootComponent
00476cde MyBrowser.exe   System.Classes       TStream.ReadComponent
00471b7f MyBrowser.exe   System.Classes       InternalReadComponentRes
00471cef MyBrowser.exe   System.Classes       InitComponent
00471d7d MyBrowser.exe   System.Classes       InitInheritedComponent
0057341a MyBrowser.exe   Vcl.Forms            TCustomForm.Create
0057df22 MyBrowser.exe   Vcl.Forms            TApplication.CreateForm
005bc649 MyBrowser.exe   MyBrowser         17 initialization
76b2ef8a kernel32.dll                         BaseThreadInitThunk

memory dump: 
0845afb0  a4 cf 45 08 4c 00 00 00 - 38 75 59 00 60 75 59 00  ..E.L...8uY.`uY.
0845afc0  90 75 59 00 f4 75 59 00 - 74 76 59 00 f4 76 59 00  .uY..uY.tvY..vY.
0845afd0  74 77 59 00 f4 77 59 00 - 74 78 59 00 f4 78 59 00  twY..wY.txY..xY.
0845afe0  74 79 59 00 f4 79 59 00 - 74 7a 59 00 f4 7a 59 00  tyY..yY.tzY..zY.
0845aff0  74 7b 59 00 f4 7b 59 00 - 74 7c 59 00 f4 7c 59 00  t{Y..{Y.t|Y..|Y.

allocation number: 1989
program up time: 529 ms
type: TVCLClientHandler
address: $845cfa4
size: 92
access rights: read/write
reference counter: 1

main thread ($cb0):
671cd312 madExcept32.dll madExceptDbg   1603 GetMemCallback
00404538 MyBrowser.exe   System          290 @GetMem
0040587a MyBrowser.exe   System          290 TObject.NewInstance
0040af04 MyBrowser.exe   System          290 TInterfacedObject.NewInstance
00405eeb MyBrowser.exe   System          290 @ClassCreate
005aff1d MyBrowser.exe   cefvcl          797 TVCLClientHandler.Create
005b03b2 MyBrowser.exe   cefvcl          891 TCustomChromium.GetClientHandler
005b009f MyBrowser.exe   cefvcl          830 TCustomChromium.Create
00478fa5 MyBrowser.exe   System.Classes      CreateComponent
004791d0 MyBrowser.exe   System.Classes      TReader.ReadComponent
00479481 MyBrowser.exe   System.Classes      TReader.ReadDataInner
004793c0 MyBrowser.exe   System.Classes      TReader.ReadData
0047f91d MyBrowser.exe   System.Classes      TComponent.ReadState
004f7aa3 MyBrowser.exe   Vcl.Controls        TControl.ReadState
004fc0bd MyBrowser.exe   Vcl.Controls        TWinControl.ReadState
00573bb9 MyBrowser.exe   Vcl.Forms           TCustomForm.ReadState
0047a343 MyBrowser.exe   System.Classes      TReader.ReadRootComponent
00476cde MyBrowser.exe   System.Classes      TStream.ReadComponent
00471b7f MyBrowser.exe   System.Classes      InternalReadComponentRes
00471cef MyBrowser.exe   System.Classes      InitComponent
00471d7d MyBrowser.exe   System.Classes      InitInheritedComponent
0057341a MyBrowser.exe   Vcl.Forms           TCustomForm.Create
0057df22 MyBrowser.exe   Vcl.Forms           TApplication.CreateForm
005bc649 MyBrowser.exe   MyBrowser        17 initialization
76b2ef8a kernel32.dll                        BaseThreadInitThunk

memory dump: 
0845cfa4  b4 fd 5a 00 01 00 00 00 - fc 1d 40 00 b4 af 45 08  ..Z.......@...E.
0845cfb4  7c aa 58 00 70 ca 58 00 - 00 00 00 00 00 00 00 00  |.X.p.X.........
0845cfc4  00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00  ................
0845cfd4  00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00  ................
0845cfe4  00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00  ................
0845cff4  00 00 00 00 b4 9f 5a 00 - 00 00 00 00              ......Z.....

What am I doing wrong?

Answer 1

Try this in your app.

On project source:

Application.Initialize;
try
    Application.MainFormOnTaskbar := True;
    Application.CreateForm(TForm1, Form1);
    Application.Run;
finally
    if Assigned(form1) then
      freeandnil(form1);
end;

and This

initialization
  ReportMemoryLeaksOnShutdown := (debugHook <> 0);

finalization
  CheckSynchronize();

The result is the same?

Answer 2

As per your G+ thread , it was commented that this is indeed a bug in DCEF3 .

Switching to to DCEF4 will be a lot easier than back-porting the fix, just look at just the immediate complexity around the handling of the created TVCLClientHandler instance :

function TCustomChromium.GetClientHandler: ICefClient;
begin
  Result := TVCLClientHandler.Create(Self, False);
end;

As a start, DCEF4 does much more here :

function TChromium.CreateClientHandler(aIsOSR : boolean) : boolean;
begin
  Result := False;

  try
    if (FHandler = nil) then
      begin
        FIsOSR   := aIsOsr;
        FHandler := TVCLClientHandler.Create(Self, FIsOSR);
        Result   := True;
      end;
  except
    on e : exception do
      if CustomExceptionHandler('TChromium.CreateClientHandler', e) then raise;
  end;
end;