delay duration'last: problems?

delay duration'last: problems?

[Maarten Landzaat]

Hi,

Our current project (DEC Ada on VAX/VMS) yielded a generic timer,
which does a "delay duration'last" when there's no work to do,
or when the callback is to be called a long time ahead in the future.

More of these timers run concurrently. Each timer is one task, with
a queue of wake-up times.

Now after those 36.4 (or something) hours, we get ACCess VIOlations.
A simple put_line after the delay is not executed.

Changing duration'last to 1 hour or 24 hours does NOT present these
problems. 

The delay is in a select statement like this:

select
	accept boo;
or	
	accept baa;
or
 	delay time_to_wait;
	do_callback;
	determine(time_to_wait);  -- if queue's empty: duration'last
end select;


Can anybody tell me why the access violations may occur?

Thanks very much!
-- 
Maarten Landzaat (gijs@mbase97.xs4all.nl)
Amsterdam, Double bass, Fender Jazz Bass, Atari ST, Roland Sound Canvas.
Listen to M-BASE music!

Re: delay duration'last: problems?

[Mats Weber]

We also had problems with this, but not on VMS. We simply changed the
delays to less than 86_400.0 seconds and everything went fine.

Another thing that you must beware of on VMS is the Timer Queue Entry
Quota (tqelm in autohorize) which must be greater than the maximum number
of pending delays in your program.

I don't know what can cause the access violation.