[fpc-devel] Threads and alot of crap continued

Michael Schnell mschnell at lumino.de
Thu Nov 9 09:22:05 CET 2006

> Yes, of course, this still *is* nothing more than an event loop, ...
A decent event loop should use an OS API to free the processor until the 
next event is scheduled:

Meta code:

    if (event in event queue) begin // this is either an OS API call or 
the event queue is done with user land means
       read event from event queue // "
      end else begin
       (sleep until a new event is detected in the event queue) // this 
needs to be an OS API call
  until false;

So there is no polling and no CPU time is wasted that might be valuable 
for other processes or threads.

Decent OS means usable include message queues and semaphores.

AFAIK, in Delphi and Lazarus this event loop is not done in the program, 
but an event scheduler provided by the GUI system is used.


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