bug#62794: 28.2; jit-lock-function enters busy loop when open """ near top of large Python program

[Nick Urbanik <nicku@nicku.org>]

1. Start emacs with emacs -Q
2. Read in a large python file (3100 lines long, more than 10,000
    characters)
3. Near the top, type the following:

def function():
    """

4. No further input is accepted.
5. CPU usage is 100% as shown in /usr/bin/top
6. type kill -USR2 {process_id_of_emacs-Q}
    and the emacs window closes.
7. From my emacs started without '-Q', when I type
    killall -USR2 emacs
    I see:
Debugger entered--entering a function:
* #f(compiled-function () #<bytecode 0x8832586cc829512>)()
   syntax-ppss()
   python-nav-end-of-statement()
   python-nav-end-of-block()
   python-info-statement-ends-block-p()
   python-nav--forward-sexp(-1 nil nil)
   python-nav-forward-sexp(-1 nil nil)
   python-nav-backward-sexp()
   python-info-docstring-p((0 nil 2196 34 nil nil 0 nil 2211 nil nil))
   python-font-lock-syntactic-face-function((0 nil 2196 34 nil nil 0 nil 2211 nil nil))
   font-lock-fontify-syntactically-region(2028 3549 nil)
   font-lock-default-fontify-region(2028 3528 nil)
   font-lock-fontify-region(2028 3528)
   #f(compiled-function (fun) #<bytecode 0x19a2bc2905dba4bd>)(font-lock-fontify-region)
   jit-lock--run-functions(2028 3528)
   jit-lock-fontify-now(2028 3528)
   jit-lock-function(2028)
   redisplay_internal\ \(C\ function\)()



In GNU Emacs 28.2 (build 1, x86_64-redhat-linux-gnu, GTK+ Version 3.24.36, cairo version 1.17.6)
  of 2023-01-28 built on buildvm-x86-04.iad2.fedoraproject.org
Windowing system distributor 'The X.Org Foundation', version 11.0.12201009
System Description: Fedora Linux 37 (Workstation Edition)

Configured using:
  'configure --build=x86_64-redhat-linux-gnu
  --host=x86_64-redhat-linux-gnu --program-prefix=
  --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
  --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
  --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
  --libexecdir=/usr/libexec --localstatedir=/var
  --sharedstatedir=/var/lib --mandir=/usr/share/man
  --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
  --with-rsvg --with-tiff --with-xpm --with-x-toolkit=gtk3 --with-gpm=no
  --with-xwidgets --with-modules --with-harfbuzz --with-cairo --with-json
  --with-native-compilation build_alias=x86_64-redhat-linux-gnu
  host_alias=x86_64-redhat-linux-gnu CC=gcc 'CFLAGS=-DMAIL_USE_LOCKF -O2
  -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches
  -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
  -Wp,-D_GLIBCXX_ASSERTIONS
  -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
  -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
  -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection'
  LDFLAGS=-Wl,-z,relro
  PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
X11 XDBE XIM XPM XWIDGETS GTK3 ZLIB

Important settings:
   value of $LANG: en_AU.utf8
   value of $XMODIFIERS: @im=ibus
   locale-coding-system: utf-8-unix

Major mode: Python

Minor modes in effect:
   yas-minor-mode: t
   highlight-indentation-mode: t
   company-mode: t
   elpy-mode: t
   pyvenv-mode: t
   flymake-mode: t
   global-auto-revert-mode: t
   display-time-mode: t
   shell-dirtrack-mode: t
   tooltip-mode: t
   global-eldoc-mode: t
   eldoc-mode: t
   show-paren-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   blink-cursor-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t
   column-number-mode: t
   line-number-mode: t
   transient-mark-mode: t
   auto-fill-mode: t

Load-path shadows:
~/elisp/asn1-mode hides /home/nicku/.emacs.d/elpa/asn1-mode-20170729.226/asn1-mode
~/elisp/yaml-mode hides /home/nicku/.emacs.d/elpa/yaml-mode-20220903.1821/yaml-mode
/home/nicku/.emacs.d/elpa/dash-20220608.1931/dash hides /usr/share/emacs/site-lisp/dash/dash
/home/nicku/.emacs.d/elpa/s-20220902.1511/s hides /usr/share/emacs/site-lisp/s/s
/usr/share/emacs/site-lisp/goodies/emacs-goodies-loaddefs hides /usr/share/emacs/site-lisp/site-start.d/emacs-goodies-loaddefs
~/elisp/yaml-mode hides /usr/share/emacs/site-lisp/yaml-mode/yaml-mode
~/elisp/startup hides /usr/share/emacs/28.2/lisp/startup
/usr/share/emacs/site-lisp/rinari/util/jump/which-func hides /usr/share/emacs/28.2/lisp/progmodes/which-func
/usr/share/emacs/site-lisp/rinari/util/ruby-mode hides /usr/share/emacs/28.2/lisp/progmodes/ruby-mode

Features:
(shadow sort flyspell ispell mail-extr emacsbug message rmc puny rfc822
mml mml-sec epa epg rfc6068 epg-config gnus-util rmail rmail-loaddefs
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils cl-print debug backtrace find-func dired-aux dired
dired-loaddefs misearch multi-isearch pylint company-oddmuse
company-keywords company-etags company-gtags company-dabbrev-code
company-dabbrev company-files company-clang company-template
company-cmake company-bbdb vc-git vc-dispatcher puppet-mode yasnippet
highlight-indentation company-capf company pcase help-fns radix-tree
elpy edmacro kmacro elpy-rpc pyvenv eshell esh-cmd esh-ext esh-opt
esh-proc esh-io esh-arg esh-module esh-groups esh-util elpy-shell
elpy-profile elpy-django s elpy-refactor diff-mode easy-mmode ido
hideshow grep etags fileloop generator xref cus-edit pp
graphviz-dot-mode use-package-ensure use-package-core finder-inf
yaml-mode generic-x server flymake-proc flymake project thingatpt post
moinmoin-mode erin jka-compr autorevert filenotify time cus-load
u-vm-color vm-autoloads comp comp-cstr warnings cl-extra help-mode
vm-version vm-vars preview-latex rx erlang-start epix derived info-look
cc-mode cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs rinari advice jump inflections findr ruby-compilation
which-func imenu inf-ruby compile text-property-search ruby-mode
emacs-goodies-loaddefs color-theme wid-edit cl cython-mode python
tramp-sh tramp tramp-loaddefs trampver tramp-integration files-x
tramp-compat shell pcomplete parse-time iso8601 time-date ls-lisp
format-spec comint ring ansi-color clang-rename clang-include-fixer
let-alist clang-format xml bbdb-loaddefs auto-loads tex-site info
package browse-url url url-proxy url-privacy url-expand url-methods
url-history url-cookie url-domsuf url-util mailcap url-handlers
url-parse auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache json subr-x map url-vars seq byte-opt gv bytecomp
byte-compile cconv cl-loaddefs cl-lib iso-transl tooltip eldoc paren
electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite emoji-zwj charscript charprop case-table
epa-hook jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice
button loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads xwidget-internal dbusbind
inotify dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 543674 74632)
  (symbols 48 30193 3)
  (strings 32 142450 5048)
  (string-bytes 1 4349803)
  (vectors 16 64845)
  (vector-slots 8 1069734 41411)
  (floats 8 186 673)
  (intervals 56 9293 0)
  (buffers 992 32))

-- 
Nick Urbanik             http://nicku.org           nicku@nicku.org
GPG: 7FFA CDC7 5A77 0558 DC7A 790A 16DF EC5B BB9D 2C24 ID: BB9D2C24