bug#25122: 24.5; function describe-variable hangs on large variables

[Boruch Baum <boruch_baum@gmx.com>]

Subject: 24.5; function describe-variable hangs on large variables

1) When evaluating function describe-variable for variable
package-archive-conteqnts, emacs hangs for minutes before I gave up.

2) Aborting vua C-g works.

3) Viewing the buffer list revealed that a *Help* buffer had begun to be
created. Its content was "package-archive-contents is a variable defined
in `package.el'. Its value is " (new-lines removed).

4) If emacs is trying to stuff into that variable (and into that *Help*
buffer) all the archive information from the archive files of my
~/.emacs.d/elpa/archives/ tree, that would be about 730kb of elisp.

In GNU Emacs 24.5.1 (x86_64-pc-linux-gnu)
 of 2016-03-19 on trouble, modified by Debian
System Description:	Devuan GNU/Linux 1.0 (jessie)

Configured using:
 `configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.5/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.5/site-lisp:/usr/share/emacs/site-lisp
 --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.5/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.5/site-lisp:/usr/share/emacs/site-lisp
 --with-x=no --without-gconf --without-gsettings 'CFLAGS=-g -O2
 -fstack-protector-strong -Wformat -Werror=format-security -Wall'
 CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-z,relro'

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
  global-anzu-mode: t
  anzu-mode: t
  ws-butler-mode: t
  dtrt-indent-mode: t
  clean-aindent-mode: t
  yas-minor-mode: t
  global-undo-tree-mode: t
  undo-tree-mode: t
  volatile-highlights-mode: t
  global-ede-mode: t
  ede-minor-mode: t
  global-semantic-idle-scheduler-mode: t
  global-semanticdb-minor-mode: t
  async-bytecomp-package-mode: t
  global-semantic-stickyfunc-mode: t
  semantic-mode: t
  helm-mode: t
  shell-dirtrack-mode: t
  projectile-mode: t
  global-company-mode: t
  company-mode: t
  override-global-mode: t
  winner-mode: t
  show-paren-mode: t
  savehist-mode: t
  desktop-save-mode: t
  delete-selection-mode: t
  tooltip-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  size-indication-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t


Features:
(shadow sort mail-extr eieio-opt emacsbug helm-command tramp-cache
conf-mode org-element org-rmail org-mhe org-irc org-info org-gnus
org-docview doc-view image-mode org-bibtex bibtex org-bbdb org-w3m
misearch multi-isearch zygospore sh-script smie executable setup-editing
help-macro sgml-mode iedit-lib rect anzu mule-util ws-butler benchmark
dtrt-indent clean-aindent-mode yasnippet undo-tree diff
volatile-highlights ede/cpp-root ede/emacs setup-cedet ede/speedbar
ede/files ede ede/base ede/auto ede/source eieio-speedbar speedbar
sb-image dframe eieio-custom wid-edit semantic/idle semantic/format
ezimage semantic/tag-ls semantic/find semantic/ctxt semantic/db-mode
semantic/db eieio-base cc-mode cc-fonts cc-guess cc-menus cc-cmds
cc-styles cc-align cc-engine cc-vars cc-defs setup-helm-gtags helm-gtags
subr-x pulse which-func setup-helm helm-projectile helm-config
async-bytecomp helm-imenu semantic/util-modes semantic/util semantic
semantic/tag semantic/lex semantic/fw mode-local cedet org org-macro
org-footnote org-pcomplete org-list org-faces org-entities noutline
outline org-version ob-sh ob-awk ob-latex ob-emacs-lisp ob ob-tangle
ob-ref ob-lob ob-table ob-exp org-src ob-keys ob-comint ob-core ob-eval
org-compat org-macs org-loaddefs cal-menu calendar cal-loaddefs imenu
helm-easymenu helm-mode helm-elisp helm-files tramp tramp-compat
tramp-loaddefs trampver shell pcomplete ffap helm-buffers helm-tags
helm-bookmark helm-locate helm-eval edebug eldoc helm-grep helm-regexp
helm-elscreen helm-adaptive helm-info info helm-types helm-external
helm-net browse-url xml helm-utils helm-help helm helm-source
helm-multi-match helm-lib smtpmail sendmail async setup-general windmove
projectile skeleton grep ibuf-ext thingatpt json epl rx company-oddmuse
company-keywords company-etags company-gtags company-dabbrev-code
company-files company-capf company-cmake company-xcode company-clang
company-semantic company-eclim company-css company-nxml company-bbdb
tempo ispell etags find-func company-dabbrev company-template company
tar-mode use-package cl diminish bind-key compile comint tool-bar
autoload lisp-mnt finder-inf mm-archive message rfc822 mml mml-sec
mailabbrev gmm-utils mailheader mm-decode mm-bodies mm-encode mail-utils
gnutls network-stream starttls url-http tls mail-parse rfc2231 rfc2047
rfc2045 ietf-drums url-gw url-cache url-auth url url-proxy url-privacy
url-expand url-methods url-history url-cookie url-domsuf url-util
mailcap url-handlers url-parse auth-source eieio byte-opt bytecomp
byte-compile cl-extra cconv eieio-core gnus-util mm-util mail-prsvr
password-cache url-vars epg xterm server warnings dired-details+
dired-details help-mode advice help-fns dired+ image-dired image-file
image dired-x dired-aux dired winner ring pcase git-blame format-spec
package epg-config bookmark cl-macs gv derived pp jka-compr ibuf-macs
ibuffer paren woman man easymenu regexp-opt ansi-color edmacro kmacro
time-date savehist desktop frameset cl-loaddefs cl-lib elec-pair delsel
tango-dark-theme debian-el debian-el-loaddefs w3m-load emacs-goodies-el
emacs-goodies-custom emacs-goodies-loaddefs easy-mmode devhelp tooltip
electric uniquify ediff-hook vc-hooks lisp-float-type tabulated-list
newcomment lisp-mode prog-mode register page menu-bar rfn-eshadow timer
select mouse jit-lock font-lock syntax facemenu font-core frame cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple
abbrev minibuffer nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote make-network-process
dbusbind gfilenotify multi-tty emacs)

Memory information:
((conses 16 582332 490741)
 (symbols 48 55652 20)
 (miscs 40 421 1843)
 (strings 32 146045 231132)
 (string-bytes 1 4264772)
 (vectors 16 55051)
 (vector-slots 8 1598839 288778)
 (floats 8 286 3294)
 (intervals 56 4525 912)
 (buffers 960 27)
 (heap 1024 62515 75886))

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