Home/ Questions/Q 7180001
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-28T17:15:23+00:00

My program have several worker threads that calling a function in a dynamically loaded

  • 0

My program have several worker threads that calling a function in a dynamically loaded DLL file. The performance is slower than calling function in EXE file. My program made using Delphi. I don’t use ShareMM. The function in DLL has many routines to read file into memory. The used calling convention is stdcall. Actually, the speed is very poor!

I have no idea since I just learned about using DLL. So what should I do to optimize the performance/speed of my program/DLL?

Sorry if my question is non sense. I am sure there is nothing wrong with my exe, I just moved my functions into DLL and the performance be slower. Please ignore disk/memory cache factor as I have mentioned the routines of my DLL.

Edited:

This is how my program load the DLL

  DLLHandle := LoadLibrary(pwchar(path));
  if DLLHandle <> 0 then
  @CheckFile := GetProcAddress(DLLHandle, 'CheckFile');

In my worker threads, I always check the function using if Assigned(CheckFile) then then call CheckFile function.

Here illustration of my function

type
TCheckFile = function(const FileName: string; var FileType: WideString) 
: Boolean; stdcall;
var
CheckFile: TCheckFile ;

Now, the code in DLL

function CheckFile(const FileName: string; var FileType: WideString)
  : boolean; stdcall;
var
  testCheckFile: TBla;
begin
  Result := false;
  testCheckFile  := TBla.Create;
  try
    if testCheckFile.DoSomeRoutine(FileName, FileType) then
      Result := true;
  finally
    testCheckFile.Free;
  end;
end;
exports CheckFile;

begin
IsMultiThread := true;
end.

What my DLL do? It plays with TFileStream like convert file to pointer.

I hope there is something wrong with my loading code and the calling code.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Code that resides in a DLL runs at just the same speed as code that resides in the host executable. It is exceedingly unlikely that moving code to a DLL will result in a discernible drop in performance.

    However, you state in comments to the question that you have also ported from Delphi 2007 to Delphi XE2. That is almost certainly the change that resulted in the performance drop.

    When measuring and comparing performance it is simply crucial to change one thing at a time so that you remove any possibility for confounding factors.

    • 0