Saving SBCL Image From Emacs Multiple Threads Error

Question

I have been playing with saving running Common Lisp images to save time upon restart and make the development more efficient. However, I am having a bit of a problem since when I run the following command in the Emacs/SLIME:

(sb-ext:save-lisp-and-die "rest-api-image" :purify t)

I get the following error. Clearly, it is complaining about seeing multiple threads. As far as I can see, these are not threads I created programmatically. Instead, these are Lisp- and Emacs-created. Is there a workaround here? Can the image still be saved?

Cannot save core with multiple threads running.

Interactive thread (of current session):
  #<THREAD "main thread" RUNNING {1000550853}>

Other threads:
  #<THREAD "Swank Sentinel" #1=waiting on:
       #<WAITQUEUE  {1004AB8003}>
     {1004AB4753}>,
  #<THREAD "control-thread" #1#
       #<WAITQUEUE  {1005BC54D3}>
     {1004D87F03}>,
  #<THREAD "reader-thread" RUNNING {1004D88063}>,
  #<THREAD "swank-indentation-cache-thread" #1#
       #<WAITQUEUE  {1004D980E3}>
     {1004D88183}>,
  #<THREAD "auto-flush-thread" RUNNING {10022FFDA3}>,
  #<THREAD "repl-thread" RUNNING {1002300003}>
   [Condition of type SB-IMPL::SAVE-WITH-MULTIPLE-THREADS-ERROR]
See also:
  SBCL Manual, Saving a Core Image [:node]

Answer 1

The Cookbook has you covered: https://lispcookbook.github.io/cl-cookbook/scripting.html

The steps involved are:

(load "my-app.asd")
(ql:quickload :my-app)
(sb-ext:save-lisp-and-die #p"my-app-binary" :toplevel #'my-app:main :executable t)

So that's a possible Makefile target:

build:
    sbcl --load my-app.asd \
         --eval '(ql:quickload :my-app)' \
         --eval "(sb-ext:save-lisp-and-die #p\"my-app\" :toplevel #my-app:main :executable t)"

but doing so with asdf is portable. Add this to your .asdf system definition:

:build-operation "program-op" ;; leave as is
:build-pathname "<binary-name>"
:entry-point "<my-package:main-function>"

and then

(asdf:make :my-package)

To build a web app, with its web server, is one step more.

To parse command line arguments, catch a C-c, put everything on CI, see the Cookbook !

ps: if you need to try things out in a bare sbcl repl, have a look at cl-repl, or even sbcli, they're better than rlwrap sbcl.