[Lazarus] Epiktimer elapsed = negative value

[Anthony Tekatch]

On Mon, 07 Jul 2014 11:28:06 +0200, Michael Schnell <mschnell at lumino.de> wrote:
> Moreover:
> 
> Even if the CPU's hardware tick counter is used, in a multi-CPU system, 
> each CPU might have it's own counter and those are not guaranteed to be 
> in sync. as the OS might move the program from one CPU to the other, 
> this method does not seem to be safe, either.

OK, thanks for the details. 

From my initial measurements, the elapsed time jumped on its own from
465ms to -4294 seconds:
 ET.Elapsed= 4.6544100000000000E-0001
 ET.Elapsed=-4.2944917280000000E+0003
That is very close to 12 hours. My test showed that this could happen
within about 30 minutes of starting at any time of day.


I only really needed something to trigger once per second (on the second
would be nice), but it needs to be reliable and multiplatform. For now I
will just watch the datetime clock for changes as follows:

     oldsec:=secondof(now);
     while RunWhile do begin
       while oldsec=secondof(now) do begin
             sleep(10);
       end;
       oldsec:=secondof(now);
       LogOneReading(); //Store successive readings (my code)
    end;


Thanks,
Anthony