Dear all, I have spent 2 days now tracking an access violation in my app which I couldn't debug well because it occured somewhere where no debug info was available, but obviously during a call to FreeLibrary.
I don't know whether I am allowed to do this or not, but as far as I have read from the Microsoft docs about using libraries [1,2] I didn't find a note that my approach is forbidden. (Of course, I may have overread it.) [1] https://learn.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-best-practices [2] https://learn.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-loadlibrarya What I did is to call LoadLibrary in a different thread than the main thread. The corresponding call to FreeLibrary on the other hand was done in the main thread. Question 1: Is this legal on Windows? If not, we're finished here and you can skip the rest ;) However, if it *is* legal, I'd need some help with FPC. Here's a minimal example: *** library dummylib; uses Classes; begin end. *** program project1; uses SysUtils, Types, Classes; type TLoadLibThread = class(TThread) procedure Execute; override; var FHandle: THandle; end; procedure TLoadLibThread.Execute; begin FHandle := LoadLibrary('dummylib.dll'); end; var h: THandle = NilHandle; begin with TLoadLibThread.Create(FALSE) do begin WaitFor; h := FHandle; Free; end; Assert (h <> NilHandle); FreeLibrary (h); end. *** The call to FreeLibrary causes an "access violation writing to address $14". I also tried to follow the advice in the "multithreaded application tutorial" in the wiki ("initialize the FPC's threading system by creating a dummy thread"), but this doesn't make any difference. I assume that I have some obviouy error and am just too blind to see, so I'd appreciate someone pointing me to it. Thanks, Thomas _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
