Re: Concurrency via isolated process/thread

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: emacs-devel@gnu.org
> Date: Wed, 05 Jul 2023 12:40:51 +0000
> 
> I imagine that there will be a special "remote Lisp object" type.
> 
> 1. Imagine that child Emacs process asks for a value of variable `foo',
>    which is a list (1 2 3 4).
> 2. The child process requests parent Emacs to put the variable value
>    into shared memory.
> 3. The parent process creates a new variable storing a link to (1 2 3
>    4), to prevent (1 . (2 3 4)) cons cell from GC in the parent process
>    - `foo#'. Then, it informs the child process about this variable.
> 4. The child process creates a new remote Lisp object #<remote cons foo#>.
> 
> 5. Now consider that child process tries (setcar #<remote cons foo#> value).
>    The `setcar' and other primitives will be modified to query parent
>    process to perform the actual modification to
>    (#<remote value> . (2 3 4))
> 
> 6. Before exiting the child thread, or every time we need to copy remote
>    object, #<remote ...> will be replaced by an actual newly created
>    traditional object.

How is this different from communicating via stdout, like we do with
start-process today?  You don't have to send only textual data via the
pipe, you can send binary data stream as well, if what bothers you is
the conversion.