Re: Multithreading

Re: Multithreading

[Robert Dewar]

No current version of GNAT allows selection of whether or not to use OS
threads, but the design certainly allows the construction of such a runtime,
or more likely selection of runtimes.

FOr example, on the SGI, we use OS threads, but it is probably not THAT
difficult to take the threads emulator we use on SunOS and get it working
on the SGI, and it should be even easier to create this kind of option
for Solaris. But we aren't doing anything along these lines at the moment.

Re: Multithreading

[Patrick D. Logan]

In article <CzAH3B.CtI@ois.com> beckwb@ois.com (R. William Beckwith) writes:

>For every multi-threaded operating system I can think of, there _is_
>an Ada compiler that uses the native O/S threads for Ada tasks.

>        Lynx            Alsys
>        OS/2            Alsys
>        OSF/1           DEC, Rational
>        OpenVMS/AXP     DEC
>        SGI             Rational
>        Sequent         Rational
>        Solaris 2.X     Sun (Rational)
>        Win NT          Alsys, Rational

>I'm sure I missing quite a few.

>The free GNAT Ada 9X compiler is built on top of a POSIX threads
>library.  Thus, it always uses O/S threads for Ada tasks.

Do any of these Adas that support OS threading also support garbage collection?

Thanks

Patrick_D_Logan@ccm.jf.intel.com
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Re: Multithreading

[David Weller]

In article <patrick_d_logan.213.000F5784@ccm.jf.intel.com>,
Patrick D. Logan <patrick_d_logan@ccm.jf.intel.com> wrote:
>In article <CzAH3B.CtI@ois.com> beckwb@ois.com (R. William Beckwith) writes:
>
>>For every multi-threaded operating system I can think of, there _is_
>>an Ada compiler that uses the native O/S threads for Ada tasks.
>
>>[list deleted]
>Do any of these Adas that support OS threading also support garbage collection?
>

Huh?  Which OS's do GC automatically?  Certainly not a large number
of the ones listed.  How did you migrate from OS threads to GC, is
there a relationship?


-- 
Proud (and vocal) member of Team Ada! (and Team OS/2)        ||This is not your
   	      Ada -- Very Cool.  Doesn't Suck.               ||  father's Ada 
For all sorts of interesting Ada tidbits, run the command:   ||________________
"finger dweller@starbase.neosoft.com | more" (or e-mail with "finger" as subj.)
      Just another dull, stodgy, non-creative developer who uses Ada.

Re: Multithreading

[Patrick D. Logan]

In article <3ah4c0$rl4@Starbase.NeoSoft.COM> dweller@Starbase.NeoSoft.COM (David Weller) writes:

>In article <patrick_d_logan.213.000F5784@ccm.jf.intel.com>,
>>Do any of these Adas that support OS threading also support garbage 
>>collection?

>Huh?  Which OS's do GC automatically?

My understanding of Ada is that it's definition allows for garbage collection, 
and that some implementations do implement garbage collection.

My question then is of the Ada implementations that support OS threads, are 
there any that also implement garbage collection such that I can have multiple 
threads running where the data is being garbage collected?


Patrick_D_Logan@ccm.jf.intel.com
Intel ProShare Teleconferencing
(503) 696-9309 FAX: (503) 696-4210

"What I envision may be impossible, but it isn't impractical."
-Wendell Berry

Re: Multithreading

[David Weller]

In article <patrick_d_logan.226.000F6995@ccm.jf.intel.com>,
Patrick D. Logan <patrick_d_logan@ccm.jf.intel.com> wrote:
>In article <3ah4c0$rl4@Starbase.NeoSoft.COM> dweller@Starbase.NeoSoft.COM (David Weller) writes:
>
>>In article <patrick_d_logan.213.000F5784@ccm.jf.intel.com>,
>>>Do any of these Adas that support OS threading also support garbage 
>>>collection?
>
>>Huh?  Which OS's do GC automatically?
>
>My understanding of Ada is that it's definition allows for garbage collection, 
>and that some implementations do implement garbage collection.
>
>My question then is of the Ada implementations that support OS threads, are 
>there any that also implement garbage collection such that I can have multiple 
>threads running where the data is being garbage collected?
>

(Somehow I always get the nuances of GC wrong, but if my statement is
wrong here, somebody will probably correct me :-)

Offhand I'd say that effect could be achieved by nesting a protected
type instance inside a Controlled type:

	protected type Multi_Thread_Data is ...

	type GC_Item is new Ada.Finalization.Controlled with record
	   Hidden : Multi_Thread_Data;
	end record;

Does a more experienced "language lawyer" want to add something in?
Am I overtrivializing here?  Norm? Tuck?



-- 
Proud (and vocal) member of Team Ada! (and Team OS/2)        ||This is not your
   	      Ada -- Very Cool.  Doesn't Suck.               ||  father's Ada 
For all sorts of interesting Ada tidbits, run the command:   ||________________
"finger dweller@starbase.neosoft.com | more" (or e-mail with "finger" as subj.)
	|"Quitting C++ isn't so difficult, provided you show as much |
	|	persistence stopping as you did starting." dweller   |

Re: Multithreading

[Robb Nebbe]

In article <3avas0$inu@Starbase.NeoSoft.COM>, dweller@Starbase.NeoSoft.COM (David Weller) writes:
|> 
|> Offhand I'd say that effect could be achieved by nesting a protected
|> type instance inside a Controlled type:
|> 
|> 	protected type Multi_Thread_Data is ...
|> 
|> 	type GC_Item is new Ada.Finalization.Controlled with record
|> 	   Hidden : Multi_Thread_Data;
|> 	end record;
|> 

I would do it the other way around. I would put a protected type around
a controlled type. I can't come up with a good justification but it
seems more natural to me.

- Robb Nebbe

Re: Multithreading

[Ted Dennison]

In article <CzAH3B.CtI@ois.com> beckwb@ois.com (R. William Beckwith) writes:
 
>For every multi-threaded operating system I can think of, there _is_
>an Ada compiler that uses the native O/S threads for Ada tasks.

>        Lynx            Alsys
>        OS/2            Alsys
>        OSF/1           DEC, Rational
>        OpenVMS/AXP     DEC
>        SGI             Rational
>        Sequent         Rational
>        Solaris 2.X     Sun (Rational)
>        Win NT          Alsys, Rational

>I'm sure I missing quite a few.

         AmigaDOS        Nothing

>The free GNAT Ada 9X compiler is built on top of a POSIX threads
>library.  Thus, it always uses O/S threads for Ada tasks.

You mean, it always uses POSIX threads, if that O/S supports it.


T.E.D.

Re: Multithreading

[Scott Leschke]

>>The free GNAT Ada 9X compiler is built on top of a POSIX threads
>>library.  Thus, it always uses O/S threads for Ada tasks.

I haven't had the opportunity to use GNAT yet although I've been
the discussions on c.l.a.  Regarding the above statement and a previous
statement made by Bob Dewar regarding the POSSIBLE performance penalty
associated with mapping Ada tasks to OS threads, does GNAT allow you
to specify whether to use OS tasking or not ?  Is this even be possible ?

Scott Leschke