Re: Async rebuild package-quickstart after packages update? was Re: 28.0.50; Proposal: slightly more efficient package-quickstart.el

[chad <yandros@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 3110 bytes --]

As near as I can tell, the moderate-sized potential problem with "just
start another full interactive session, and communicate with it" is the
near-certainty that some people's interactive startup isn't (effectively)
reentrant. There are lots of ways this can happen -- package auto-loading
and refreshing, cache files like desktop/places/recent/history/etc,
configurations that automatically open dedicated frames in various places,
multiple servers confusing emacsclient, and the like. (Back in the 90's and
early 00's, I used to see user configurations like this all the time.)

There is some mitigation for this effect in that it overlaps with
daemon-mode non-rerentrancy, and also some in that only a subset of users
will use package-quickstart. That's probably enough to put together an
experiment, but I would expect some (solvable!) problems to crop up.

On the other hand, if I understand T.V Raman's suggestion to put together a
package that learns which parts of the environment are necessary to share
between a configured emacs and a subsequent emacs batch process, it sounds
like a reasonable approach toward a similar middle ground, but starting
from the cleaner -Q state. If I'm reading async.el correctly, it already
has machinery for this in, for example, async-inject-variable.

(defun async-inject-variables

    (include-regexp &optional predicate exclude-regexp noprops)  "Return a
> `setq' form that replicates part of the calling environment.
> It sets the value for every variable matching INCLUDE-REGEXP and
> also PREDICATE.  It will not perform injection for any variable
> matching EXCLUDE-REGEXP (if present) or representing a `syntax-table'
> i.e. ending by \"-syntax-table\".
> When NOPROPS is non nil it tries to strip out text properties of each
> variable's value with `async-variables-noprops-function'.
> It is intended to be used as follows:
>     (async-start
>        \\=`(lambda ()
>           (require \\='smtpmail)
>           (with-temp-buffer
>             (insert ,(buffer-substring-no-properties (point-min)
> (point-max)))
>             ;; Pass in the variable environment for smtpmail
>             ,(async-inject-variables
> \"\\\\=`\\(smtpmail\\|\\(user-\\)?mail\\)-\")
>             (smtpmail-send-it)))
>        \\='ignore)"


It also has this option, which suggests that this issue comes up at least
some of the time, and is worked around in situ rather than solved at the
package level:

(defvar async-quiet-switch "-Q"
>   "The Emacs parameter to use to call emacs without config.
> Can be one of \"-Q\" or \"-q\".
> Default is \"-Q\" but it is sometimes useful to use \"-q\" to have a
> enhanced config or some more variables loaded.")


I think there's an interesting area to explore here, especially given the
relatively low utility of make-thread, the way cores are multiplying, and
the extra crunching-power desired by potential changes like native-comp,
json, lsp, and tree-sitter (which I assume, perhaps wrongly, will end up
with loadable binary objects for some/most languages), this seems like a
good problem to look at.

Hope that helps,
~Chad

[-- Attachment #2: Type: text/html, Size: 3925 bytes --]