GNU bug report logs - #80140
30.1.90; jsonrpc-shutdown does not wait its full timeout if the process has output

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Aaron Zeng <azeng <at> janestreet.com>
To: bug-gnu-emacs <at> gnu.org
Cc: app-emacs-dev <at> janestreet.com, azeng <at> janestreet.com
Subject: 30.1.90; jsonrpc-shutdown does not wait its full timeout if the
 process has output
Date: Tue, 06 Jan 2026 12:18:56 -0500

Hello,

I have noticed that jsonrpc-shutdown (called by eglot-shutdown)
sometimes does not wait the full 100ms timeout for the process to exit
and instead calls delete-process (sending SIGKILL) very quickly after
being called.  For example, here is some output from attempting to shut
down ocaml-lsp using M-x eglot-shutdown:

    [jsonrpc] e[17:11:23.652] --> shutdown[4] {"jsonrpc":"2.0","id":4,"method":"shutdown","params":{}}
    [stderr]  2025-12-19 17:11:23.652551-05:00 Info ("request:shutdown                 (azeng:11)"(category request)(event_index 11)(action shutdown)(feature())(file())(lines())(hash())(position())(info())) -- [program: ocaml-lsp-server]
    [jsonrpc] e[17:11:23.653]   <-- shutdown[4] {"id":4,"jsonrpc":"2.0","result":null}
    [jsonrpc] e[17:11:23.653] --> exit {"jsonrpc":"2.0","method":"exit","params":{}}
    [stderr]  2025-12-19 17:11:23.653406-05:00 Info ("Priority_lsp_executor queue stats"(action"just after dequeue: Eof")(realtime_size 0)(background_size 0)(total_size 0)) -- [program: ocaml-lsp-server]
    [jsonrpc] D[17:11:23.664] Connection state change: `killed

From the timestamps, you can see that the connection was killed a mere
11ms after the exit request notification was sent, rather than the
expected 100ms.  I believe this is due to the fact that jsonrpc-shutdown
will only call accept-process-output once, but that function may return
sooner than 100ms if the process produces some stdout/stderr output and
runs a process filter:

      (cl-loop
       with proc = (jsonrpc--process conn) for i from 0
       while (not (process-get proc 'jsonrpc-sentinel-cleanup-started))
       unless (zerop i) do
       (jsonrpc--warn "Sentinel for %s still hasn't run, deleting it!" proc)
       (delete-process proc)
       do
       ;; Let sentinel have a chance to run
       (accept-process-output nil 0.1))

In order to allow a full 100ms for the process to exit, I think this
instead needs to loop and call accept-process-output multiple times,
perhaps using with-timeout like so:

    do
    ;; Let sentinel have a chance to run
    (with-timeout (0.1)
      (while (not (process-get proc 'jsonrpc-sentinel-cleanup-started))
        (accept-process-output)))

With the above code installed locally, I see that eglot-shutdown waits
the full 100ms on a nonresponsive language server before SIGKILLing it.
Please feel free to reimplement to taste :)

Thanks,
Aaron


In GNU Emacs 30.1.90 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.15.12, Xaw scroll bars) of 2025-12-17 built on
 igm-qws-u12685a
Repository revision: b16b92282c83c51818a55c9f7a241596e876ad4e
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Rocky Linux 8.10 (Green Obsidian)

Configured using:
 'configure --with-x-toolkit=lucid --without-gpm --without-gconf
 --without-selinux --without-imagemagick --with-modules --with-gif=no
 --with-cairo --with-rsvg --without-compress-install --with-tree-sitter
 --with-native-compilation=aot
 --prefix=/usr/local/home/garnish/raw-emacs/30-20251217_145705'

Configured features:
CAIRO DBUS FREETYPE GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG LIBSYSTEMD
LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP
SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER X11 XDBE XIM
XINPUT2 XPM LUCID ZLIB

Important settings:
  value of $EMACSLOADPATH: /usr/local/home/azeng/workspaces/24833141-bffb-3c99-a9d6-c366d37c4f5e/+share+/app/emacs/elisp:/usr/local/home/azeng/workspaces/24833141-bffb-3c99-a9d6-c366d37c4f5e/+share+/app/emacs/site-lisp:
  value of $LANG: en_US.utf8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
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  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
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inotify dynamic-setting system-font-setting font-render-setting cairo
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native-compile emacs)

Memory information:
((conses 16 58500 9886) (symbols 48 5519 3) (strings 32 22158 1681)
 (string-bytes 1 579161) (vectors 16 9202)
 (vector-slots 8 128678 7990) (floats 8 25 2) (intervals 56 276 0)
 (buffers 992 11))

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