Thread: [Tcl-Threads] Shared object

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Hi!

How can i share an object between two thread?

Laci
Use thread shared variables.
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/tcl/thread/doc/=
html/tsv.html

	-----Urspr=FCngliche Nachricht-----
	Von: Laci [mailto:fo...@fr...]=20
	Gesendet: Mittwoch, 16. Juli 2003 16:16
	An: tcl...@li...
	Betreff: [Tcl-Threads] Shared object
=09
=09
	How can i share an object between two thread?
	=20

On Wednesday 16 July 2003 20:55, you wrote:
> Example:
>
> class Auto {
>     variable _color ""
>
>     public method setColor {color} {set _color $color}
>     public method getColor {} {return $_color}
>
>     public proc new {} {return [Auto ::#auto]}
> }
>
> set audi [Auto::new]
> $audi setColor red
>
> Can i share audi variable (object)?
>

Now, we're gettting closer....
And the answer is: no.

Rationale....

Tcl uses the compartment threading model where all 
resources created by Tcl in an Tcl interpreter are always
bound to that interpreter. Examples are: channles, commands,
namespaces, etc. Now, since Tcl interps are bound to a thread
that created them, you can not share mentioned Tcl resources.

The only way one could achieve this would be to write the object
serializer which synthetizes a Tcl script representing the object
and then pass this script to the remote thread to re-create 
the object. That is, some kind of object marshalling would be needed.

I know you wont't be very happy with the answer. I'm not either.
But out of my experience (I use XOTcl instead of incrTcl)
I'm able to work-arround this limitation quite successfully and 
have written quite a complicated MT-application using OO 
constructs and threads.

Zoran

I see!

But i have read this: (link:
http://groups.yahoo.com/group/tcl_announce/message/1361)

Summary of Changes since version 2.2:
-------------------------------------

o. New set of thread shared variable commands. It is a complete
rewrite, allowing you to store Tcl objects in thread shared arrays.
In the previous release, only the object string representation
has been stored, affecting performance when building large and
complex shared data structures. Much care has been taken internally
to get a safe and protected shared object storage w/o explicit
external locking. It is now very fast and convenient to use.
All new commands reside under the "tsv::" namespace. For the
backward compatility with the 2.2 version, all sv_* commands are
still available. Please note that support for those might be
dropped in future (major) releases of the extension.

Laci

> On Wednesday 16 July 2003 20:55, you wrote:
> > Example:
> >
> > class Auto {
> >     variable _color ""
> >
> >     public method setColor {color} {set _color $color}
> >     public method getColor {} {return $_color}
> >
> >     public proc new {} {return [Auto ::#auto]}
> > }
> >
> > set audi [Auto::new]
> > $audi setColor red
> >
> > Can i share audi variable (object)?
> >
>
> Now, we're gettting closer....
> And the answer is: no.
>
> Rationale....
>
> Tcl uses the compartment threading model where all
> resources created by Tcl in an Tcl interpreter are always
> bound to that interpreter. Examples are: channles, commands,
> namespaces, etc. Now, since Tcl interps are bound to a thread
> that created them, you can not share mentioned Tcl resources.
>
> The only way one could achieve this would be to write the object
> serializer which synthetizes a Tcl script representing the object
> and then pass this script to the remote thread to re-create
> the object. That is, some kind of object marshalling would be needed.
>
> I know you wont't be very happy with the answer. I'm not either.
> But out of my experience (I use XOTcl instead of incrTcl)
> I'm able to work-arround this limitation quite successfully and
> have written quite a complicated MT-application using OO
> constructs and threads.
>
> Zoran
>
>
>
>
>

On Thursday 17 July 2003 11:17, Laci wrote:
> I see!
>
> But i have read this: (link:
> http://groups.yahoo.com/group/tcl_announce/message/1361)
>
> Summary of Changes since version 2.2:
> -------------------------------------
>
> o. New set of thread shared variable commands. It is a complete
> rewrite, allowing you to store Tcl objects in thread shared arrays.

Please do not confuse Tcl_Obj structures, which are C-level 
constructs with inctTcl objects which are special interp 
namespace/commands. 

Although Tcl_Obj* structures should *not* be shared between
threads beacuse of lack of locking, I managed to create an
safe-environment using thread shared arrays where one can
safely store Tcl_Obj in shared memory and operate on them
w/o making the string rep each time.
But, this was not the scope of your question.

Thread shared varaibles (arrays) are means of transfering
scalar values (data) between threads, while retaining their
internal representation. This feature won't help you with
incrTcl objects which are combination of commands and data.

Cheers
Zoran 

Thank you!

Laci

> On Thursday 17 July 2003 11:17, Laci wrote:
> > I see!
> >
> > But i have read this: (link:
> > http://groups.yahoo.com/group/tcl_announce/message/1361)
> >
> > Summary of Changes since version 2.2:
> > -------------------------------------
> >
> > o. New set of thread shared variable commands. It is a complete
> > rewrite, allowing you to store Tcl objects in thread shared arrays.
> 
> Please do not confuse Tcl_Obj structures, which are C-level 
> constructs with inctTcl objects which are special interp 
> namespace/commands. 
> 
> Although Tcl_Obj* structures should *not* be shared between
> threads beacuse of lack of locking, I managed to create an
> safe-environment using thread shared arrays where one can
> safely store Tcl_Obj in shared memory and operate on them
> w/o making the string rep each time.
> But, this was not the scope of your question.
> 
> Thread shared varaibles (arrays) are means of transfering
> scalar values (data) between threads, while retaining their
> internal representation. This feature won't help you with
> incrTcl objects which are combination of commands and data.
> 
> Cheers
> Zoran 
> 
> 
> 

Thread: [Tcl-Threads] Shared object

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