Delphi DLL - thread safe

Question

I have a Delphi DLL and I want to load it in my app inside a thread (more than one, to be exactly). The DLL just creates a object, then it uses it and destroys it. For that

Answer 1

If you are careful about what you do in the thread, you'll be ok. If you need to update the VCL of the main thread, use synchronize, or better yet, don't.

I have a big DLL where I do lots of database access, and it runs in a thread. Everything worked great in my unit tests, but blew up sky high when run within a thread in the main app. Turns out, I had to re-read the database docs on thread safety. In my case, it's DBISAM and I just had to be sure to create a new session for the threaded database instance, so it wouldn't collide with the main one.

Another place where I ran into trouble (again, worked great in unit tests, failed in threads) is with XML handling. I had to call CoInitialize/CoUnInitialize before/after using the XML DOM stuff. This holds true for any SOAP stuff, which uses the XML DOM under the hood.