[fpc-pascal] Reproducible code: DLL calling Firebird crashes

Mark Morgan Lloyd markMLl.fpc-pascal at telemetry.co.uk
Mon Sep 29 11:19:08 CEST 2014

Reinier Olislagers wrote:
> Apparently my crashes in a dll that use Firebird have to do with
> initialization sections in my business layer creating a single instance
> of my db layer.
> Distilled reproducible code that demonstrates problem:
> https://bitbucket.org/reiniero/fpc_laz_patch_playground/downloads/dllcrash.zip
> 1. Please update your Firebird server details in dbinterface.pas to your
> situation (hostname etc)
> 2. In businesslayer.pas, $define CRASH to see the problem.
> The code in question is:
> initialization
>   DBLayer:=TDBInterface.Create;
> finalization
>   DBLayer.Free;
> ... so probably initialization order plays a part?!?
> How should I fix this?

What happens if you move the responsibility for initialising and closing 
the database connection to the app-level code? In other words, the app 
does something like

   writeln('Starting demo');
   writeln('TheAnswer is:');
   writeln('Ending demo');

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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