Subject: bug#71367: 30.0.50; ELPA package breadcrumb causes Emacs freeze when editing json file

From: Tassilo Horn <[email-masked]>
Date: Tue, 04 Jun 2024 21:40:50 +0200

I use and like the breadcrumb ELPA package.

  https://elpa.gnu.org/packages/breadcrumb.html

It's installed/enabled using:

--8<---------------cut here---------------start------------->8---
(use-package breadcrumb
  :ensure t
  :init (breadcrumb-mode 1))
--8<---------------cut here---------------end--------------->8---

Now when I find the attached mirrorstatus.json using json-ts-mode (that
seems to be important), set point on the first { and insert some spaces,
Emacs will eventually freeze for several seconds or even minutes.

It can be reproduced with

  emacs -Q
  M-x package-initialize RET
  M-: (package-activate 'breadcrumb) RET
  M-x breadcrumb-mode RET

and then finding the file and doing as written above.

I've also attached a gdb backtrace which suggests that emacs is
collecting garbage (produced by the breadcrumb ELN code)?  I've also
tried profiler-start, reproduce the freeze, wait for it to go away,
profiler-report.  That said that 99% of cpu time where spent in
Automatic GC.

I currently have no emacs without native compilation handy so I cannot
tell if that's important, too.  Can I somehow tell emacs not to compile
breadcrumb natively after deleting the eln file?

In GNU Emacs 30.0.50 (build 13, x86_64-pc-linux-gnu, GTK+ Version
 3.24.42, cairo version 1.18.0) of 2024-06-04 built on thinkpad-t440p
Repository revision: 799f78a92c6c31f4d181390523b83d036020ede1
Repository branch: master
System Description: Arch Linux

Configured using:
 'configure --with-tree-sitter --with-pgtk --with-modules'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY
PDUMPER PGTK PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XIM GTK3 ZLIB

Important settings:
  value of $LC_MONETARY: de_DE.utf8
  value of $LC_NUMERIC: de_DE.utf8
  value of $LC_TIME: de_DE.utf8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: mu4e:main

Minor modes in effect:
  breadcrumb-mode: t
  editorconfig-mode: t
  global-aggressive-indent-mode: t
  pdf-occur-global-minor-mode: t
  diredfl-global-mode: t
  mu4e-search-minor-mode: t
  mu4e-update-minor-mode: t
  mu4e-context-minor-mode: t
  mu4e-modeline-mode: t
  which-key-mode: t
  highlight-parentheses-mode: t
  global-git-commit-mode: t
  magit-auto-revert-mode: t
  corfu-popupinfo-mode: t
  corfu-history-mode: t
  global-corfu-mode: t
  corfu-mode: t
  vertico-mode: t
  marginalia-mode: t
  minibuffer-depth-indicate-mode: t
  switchy-window-minor-mode: t
  electric-pair-mode: t
  recentf-mode: t
  override-global-mode: t
  repeat-mode: t
  global-so-long-mode: t
  save-place-mode: t
  savehist-mode: t
  puni-global-mode: t
  puni-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  buffer-read-only: t
  column-number-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  overwrite-mode: overwrite-mode-binary

Load-path shadows:
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~/Repos/el/mu/mu4e/mu4e-context hides ~/Repos/el/mu/build/mu4e/mu4e-context
~/Repos/el/mu/mu4e/mu4e-main hides ~/Repos/el/mu/build/mu4e/mu4e-main
~/Repos/el/mu/mu4e/mu4e-vars hides ~/Repos/el/mu/build/mu4e/mu4e-vars
~/Repos/el/mu/mu4e/mu4e-window hides ~/Repos/el/mu/build/mu4e/mu4e-window
~/Repos/el/mu/mu4e/mu4e-speedbar hides ~/Repos/el/mu/build/mu4e/mu4e-speedbar
~/Repos/el/mu/mu4e/mu4e-view hides ~/Repos/el/mu/build/mu4e/mu4e-view
~/Repos/el/mu/mu4e/mu4e-thread hides ~/Repos/el/mu/build/mu4e/mu4e-thread
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~/Repos/el/mu/mu4e/mu4e-org hides ~/Repos/el/mu/build/mu4e/mu4e-org
~/Repos/el/mu/mu4e/mu4e-lists hides ~/Repos/el/mu/build/mu4e/mu4e-lists
~/Repos/el/mu/mu4e/mu4e-actions hides ~/Repos/el/mu/build/mu4e/mu4e-actions
~/Repos/el/mu/mu4e/mu4e-helpers hides ~/Repos/el/mu/build/mu4e/mu4e-helpers
~/Repos/el/mu/mu4e/mu4e-search hides ~/Repos/el/mu/build/mu4e/mu4e-search
~/Repos/el/mu/mu4e/mu4e-server hides ~/Repos/el/mu/build/mu4e/mu4e-server
~/Repos/el/mu/mu4e/mu4e-obsolete hides ~/Repos/el/mu/build/mu4e/mu4e-obsolete
~/Repos/el/mu/mu4e/mu4e-update hides ~/Repos/el/mu/build/mu4e/mu4e-update
~/Repos/el/mu/mu4e/mu4e-draft hides ~/Repos/el/mu/build/mu4e/mu4e-draft
~/Repos/el/mu/mu4e/mu4e-message hides ~/Repos/el/mu/build/mu4e/mu4e-message
~/Repos/el/mu/mu4e/mu4e-compose hides ~/Repos/el/mu/build/mu4e/mu4e-compose
~/Repos/el/mu/mu4e/mu4e-headers hides ~/Repos/el/mu/build/mu4e/mu4e-headers
~/Repos/el/mu/mu4e/mu4e-query-items hides ~/Repos/el/mu/build/mu4e/mu4e-query-items
~/Repos/el/mu/mu4e/mu4e-notification hides ~/Repos/el/mu/build/mu4e/mu4e-notification
~/Repos/el/mu/mu4e/mu4e-contacts hides ~/Repos/el/mu/build/mu4e/mu4e-contacts
~/Repos/el/mu/mu4e/mu4e-icalendar hides ~/Repos/el/mu/build/mu4e/mu4e-icalendar
~/Repos/el/mu/mu4e/mu4e-mark hides ~/Repos/el/mu/build/mu4e/mu4e-mark
~/Repos/el/mu/mu4e/mu4e-contrib hides ~/Repos/el/mu/build/mu4e/mu4e-contrib
~/Repos/el/mu/mu4e/mu4e-folders hides ~/Repos/el/mu/build/mu4e/mu4e-folders
~/Repos/el/mu/mu4e/mu4e-mime-parts hides ~/Repos/el/mu/build/mu4e/mu4e-mime-parts
/home/horn/.emacs.d/elpa/ef-themes-1.7.0/theme-loaddefs hides /home/horn/Repos/el/emacs/lisp/theme-loaddefs
/home/horn/.emacs.d/elpa/transient-20240603.2200/transient hides /home/horn/Repos/el/emacs/lisp/transient

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lcms2 multi-tty move-toolbar make-network-process native-compile emacs)

Memory information:
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 (string-bytes 1 7336948) (vectors 16 88961) (vector-slots 8 1039766 63137)
 (floats 8 784 130) (intervals 56 1927 97) (buffers 992 19))