The following code (Msg is just outputting to the debug monitor) will produce something strange:
// replace all line endings with space
for Pos1 := 1 to Len do begin
try
Msg(2, 'GetVector', Format(' %d %d',[Pos1, Len]));
if Line[Pos1] = #13 then Line[Pos1] := ' ';
if Line[Pos1] = #10 then Line[Pos1] := ' ';
except
on e: Exception do
Msg(2, 'GetVector', Format('e %d %d %s',[Pos1, Len, e.message]));
end;
end;Show quoted text 23 lines
and so on.
This is not the only code that fails in strange ways! I wondered all the time why I got random non-deterministic crashes all the time and only when I inserted these debug message outputs into this loop the nature of the problem became more clear.
The code in question is running in a dll that is loaded by a the proprietary software Metatrader 4 (through their proprietary scripting language) and it does not much more than having a TProcess in which Rterm.exe (the R-Project) is running (and idle) and there are two pipes for the stdio of this process but they are empty and idle when this happens. I have no other threads started when this happens (of course Metatrader has a few) but not my dll and nothing calls into my dll when this happens.
FPC is 2.5.1 trunk.
There are no OS exceptions happening because I have another dll with an exception handler hooked into AddVectoredExceptionHandler() as the very forst handler that does reliable log all these windows exceptions (AV, FPU, etc).
What could cause this strange effect? What kind of outside force can make this thread raise an FPC native exception although it does not come anywhere near a raise statement? Maybe there is something wrong in the DLLMain when the attach_thread event happens? does it mess up this thread ID (or however the raise mechanism works) with something else?
Maybe something else is permanently calling raise and random other threads are catching it?
confused,
Bernd