Re: Ada and Unix--Blocked Tasks

[cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!cs.u mn.edu!sctc.com!stachour@ucbvax.Berkeley.EDU (Paul Stachour)]

   The methods indicated here seem kind-of wierd to me.  After all,
an Ada task is SUPPOSED to be an independent thread-of-control.
And when I do something in Ada, I expect the run-time to arange to leave
my other tasks alone, and only block the one needing the service.

   Now I understand that IF I import some non-Ada, specialized-system
stuff into my Ada task, when I call it, it might have loads to do,
and block till done.  But that's what tasks are for!

   Doing the system-specific, unix-style signals seems to me to
be at odds with doing things in Ada with tasks, yes?

   But then my first two experiences with Ada were with the
Honeywell GCOS6 and GCOS8 systems.  In the first, commands
were normally done as tasks (as in Unix), and the Ada compiler
and run-time adopted to OS mechanism to give the natural Ada
parallelism by spawning an OS task whenever Ada would spawn
an Ada task.  And in GOCS8, they used the batch/tss subtask
mechanism to accomplish the same results.  Thus Ada tasks acted
as they should, like real tasks.

   Which leads us to the basic question:

     If the Ada system you are using can't do tasking "correctly"
(i.e., in a non-blocking way) in its implementation, what is in
error?

   Is it the OS (unix in this case)?
   Your Ada compiler vendor (Don't know who)?
   Your Ada run-time vendor?
   Or something else?

   Yours, ...Paul



  
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Paul Stachour          SCTC, 1210 W. County Rd E, Suite 100           
stachour@sctc.com          Arden Hills, MN  55112-3739
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