How to configure FastMM to detect memory leak in a dll - delphi

Question

I can't figure out how to detect memory leaks in a statically or even dynamically linked dll. I just want to detect the leaks in the dll, and I don't want to share the memory manager between the dll, and the app. Additionally the dll is linked with runtime packages
My sample dll looks like this:
library dll;
uses
fastmm4,
System.SysUtils,
System.Classes;
{$R *.res}
procedure MyInit; stdcall;
Begin
TObject.Create;
End;
exports MyInit;
begin
end.
application dpr:
program app;
uses
//fastmm4,
Vcl.Forms,
main in 'main.pas' {Form1};
{$R *.res}
begin
Application.Initialize;
Application.MainFormOnTaskbar := True;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.
Note: If I uncomment fastmm4, than I can detect the memleak caused by the application (TStringList.Create), but not the leak in the dll.
And in the application main unit:
unit main;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
private
LDLLHandle: HModule;
LShowProc: TProcedure;
end;
var
Form1: TForm1;
{$ifdef static}
procedure MyInit; stdcall; external 'dll.dll';
{$endif}
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
begin
TStringList.Create;
{$ifdef static}
MyInit;
{$else}
LDLLHandle := LoadLibrary('dll.dll');
if LDLLHandle <> 0 then
begin
try
LShowProc := GetProcAddress(LDLLHandle, 'MyInit');
if Assigned(LShowProc) then
LShowProc;
finally
FreeLibrary(LDLLHandle);
end;
end;
{$endif}
end;
end.
I expect from FastMM to generate a report when FreeLibrary is called, or on program exit, if the dll is statically loaded, but nothing happens.
In the FastMM4Options.inc I additionally just set FullDebugMode and ClearLogFileOnStartup, and the FastMM_FullDebugMode.dll is in the output directory.
I created a repository on github. What am I missing?

Answer 1

The reason that your DLL is not reporting leaks stems from this code in the FastMM shutdown:
CheckBlocksOnShutdown(
{$ifdef EnableMemoryLeakReporting}
True
{$ifdef RequireIDEPresenceForLeakReporting}
and DelphiIsRunning
{$endif}
{$ifdef RequireDebuggerPresenceForLeakReporting}
and ((DebugHook <> 0)
{$ifdef PatchBCBTerminate}
or (Assigned(pCppDebugHook) and (pCppDebugHook^ <> 0))
{$endif PatchBCBTerminate}
)
{$endif}
{$ifdef ManualLeakReportingControl}
and ReportMemoryLeaksOnShutdown
{$endif}
{$else}
False
{$endif}
);
In your options, RequireDebuggerPresenceForLeakReporting is defined. What's more, in the DLL, DebugHook is equal to 0, presumably because you are debugging the application rather than the DLL. This means that you call CheckBlocksOnShutdown passing False. And that False disables reporting of leaks.
You can resolve this by undefining RequireDebuggerPresenceForLeakReporting.

Answer 2

I just test it with version Fast Memory Manager 4.97 on Delphi2010 - win7
FastMM4 is the first unit in the 'uses' clause of the .dpr (project and dll)
'ShareMM' option is enabled
'AttemptToUseSharedMM' option is enabled
'EnableMemoryLeakReporting' option is enabled
Add FastMM_FullDebugMode.dll in the folder of the exe
There is also a test demo 'Dynamically Loaded DLL'
This demo is without the ShareMem.
I must set the option 'ShareMM' and 'AttemptToUseSharedMM' enabled and add the FastMM_FullDebugMode.dll to have a leak report of FastMM.