Re: Concurrency via isolated process/thread

[Po Lu]

Ihor Radchenko <yantar92@posteo.net> writes:

> Mostly because it will involve more changes than I was hoping for. 

Fundamental changes to the Emacs Lisp runtime will unavoidably involve
an immense number of changes, of course.

> And I am not sure how things will affect memory alignment of symbol
> objects (I do not fully understand the relevant comments in lisp.h)

How is any of this relevant to symbol alignment?  Please tell us which
comments you're referring to.

> we should be careful about concurrent read access to struct slots in
> shared objects.

Fortunately, there are very few direct references to fields within
Lisp_Symbol.

> If there is some memory re-alignment happening concurrently, we may
> either have to use READ_ONCE (and degrade performance) or be extra
> careful to ensure that memory does not get shifted around, and we do
> not end up trying to read wrong memory address because some other
> thread wrote staff into the same symbol during the read.

Memory re-alignment?