Delphi multithreading and DLL exports: watch your exceptions (via: Stack Overflow)
Posted by jpluimers on 2014/06/03
Talking about Danny Thorpe: he also posted a nice hint on threading methods for ancient Delphi versions that equally applies to DLL exports in any Delphi version, even any programming environment.
Recently, I had to do some surgery in such a Pre-Delphi 6 application, and I was really happy to remember this answer: it instantly solved some process crashes, and the added logging allowed for investigating the actual cause.
Note that this tip isn’t just a good advice for old Delphi versions.
Even in younger Delphi versions, you have to watch methods that can be called from outside a regular Delphi context, for instance exported methods.
Heck, it applies to virtually any development environment: exceptions usually are very specific to that environment and should never cross a process boundary.
Summary
Take the approach below
- for Execute methods in your own thread classes in Delphi 5 or earlier
- for any method that can be called externally (like DLL exports)
[sourcecode language=”pascal”]
procedure ThreadExecuteOrDllExport(…);
begin
try
CallInternalLogic(…parameters…);
except
on e: Exception do
begin
// output or log this error somewhere.
end;
end;
end;
[/sourcecode]
–jeroen
via: multithreading – Program shutdown on Synchronize – Stack Overflow.
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