Hello everyone, I've been debgging a weird problem I was having with a little app of mine. I'm using the latest stable Lazarus and FreePascal. The same project on Windows runs fine. On Linux (Debian Sid) fires an exception when running the finalization code.
I narrowed the problem to the use of Log4D (svn head from SF). Simply adding Log4D to the uses list is enough to make the application fail on exit.
Long-history-short, the culprit code is this:
constructor TLogLog.Create;
begin
inherited Create('');
Appender := ;
AddAppender(TLogODSAppender.Create(''));
InternalDebugging := False;
Level := Log4D.Debug;
end;There's a LogLog variable that is destroyed in the finalization section (and fails). The problem is that the TLogODSAppender created in the ctor ends up destroyed inside the AddAppender call. This is the AddAppender code:
procedure TLogLogger.AddAppender(const Appender: ILogAppender);
begin
LockLogger;
try
if FAppenders.IndexOf(Appender) = -1 then
begin
FAppenders.Add(Appender);
if FHierarchy nil then
FHierarchy.FireAppenderEvent(True, Self, Appender);
end;
finally
UnlockLogger;
end;
end;The appender dtor is called inside the call to IndexOf (it seems by the stack trace because it's use-count reaches zero). So: The appender is destroyed before is adding it to the list and later the TLogLog dtor fails when tries to destroy it again.
I already solved the problem, but don't know why. Changing the TLogLog.Create code by this one makes the problem disappear:
constructor TLogLog.Create;
var
Appender: ILogAppender;
begin
inherited Create('');
Appender := TLogODSAppender.Create('');
AddAppender(Appender);
InternalDebugging := False;
Level := Log4D.Debug;
end;Who is at fault here? Log4D? The compiler? Me?
Any hints will be appreciated...
/MRC