[fpc-devel] Threads and alot of crap continued

Michael Schnell mschnell at lumino.de
Wed Nov 8 13:19:14 CET 2006

Micha Nelissen wrote:
> Michael Schnell wrote:
>> An asynchronous timer needs to do a preemptive callback. 
> No.
Ooops ? What is an asynchronous timer according to your definition ?

>> Preemptive execution needs it's own thread. 
> No.
Ooops ? What do you think is preemptive ? By definition preemption means 
that according to a hardware event the execution of a line of code can 
be "preempted" by other code an any position. As I understand it this is 
only possible by threads or processes or by multiple CPUs (that are by 
the OS are handled as Threads, as well)
> Preemptive means same thread, as it 'preempts' it. That's what a 
> (unix) signal is. That's what Vincent meant (I think).
OK, a signal is a special kind of (preemptive) thread that the OS can 

IMHO it's not a good idea to have pascal code run in the context of a 
signal. I feel that restrictions that might hold here ask for lots of 

Moreover FPC is a lot about platform independency and signals are not an 
option in all supported platforms.


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