bug#26710: Fwd: 25.2; project-find-regexp makes emacs use 100% cpu

[Hariharan Rangasamy <hariharanrangasamy@gmail.com>]

using project-find-regexp to find text in a folder makes emacs use 100%
CPU

Steps to reproduce:
1. emacs -nw -Q
2. M-x project-find-regexp
3. choose search item as emacs
4. Choose the project as downloaded emacs-25.2/ folder
5. Give top command and check the cpu usage of emacs-25.2 process
6. emacs utilises 100% CPU till the search is over.






In GNU Emacs 25.2.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.18.9)
 of 2017-04-29 built on hari-laptop
System Description:     Ubuntu 16.04.2 LTS

Configured features:
XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS NOTIFY GNUTLS FREETYPE XFT
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11

Important settings:
  value of $LANG: en_IN
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: iso-latin-1-unix

Major mode: Fundamental

Minor modes in effect:
  shell-dirtrack-mode: t
  diff-auto-refine-mode: t
  tooltip-mode: t
  global-eldoc-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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
user-error: No matches for: helloworld
Using ’~/Downloads/emacs-25.2/’ as a transient project root
Enriched: decoding document...
Indenting...
Using ’~/Downloads/emacs-25.2/’ as a transient project root
Enriched: decoding document...
Indenting...
Making completion list...
delete-backward-char: Text is read-only
user-error: Beginning of history; no preceding item [2 times]
Quit [2 times]

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rfc822 mml mml-sec epg
epg-config mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mail-utils
autoconf autoconf-mode m4-mode gud nroff-mode texinfo sgml-mode python
tramp-sh tramp tramp-compat auth-source mm-util mail-prsvr
password-cache tramp-loaddefs trampver ucs-normalize advice json map seq
semantic/bovine/grammar semantic/wisent/grammar semantic/bovine
semantic/grammar help-fns semantic/idle semantic/grammar-wy bat-mode
cc-awk enriched cc-mode cc-fonts cc-guess cc-menus cc-cmds cc-styles
cc-align cc-engine cc-vars cc-defs nxml-uchnm rng-xsd xsd-regexp
rng-cmpct rng-nxml rng-valid rng-loc rng-uri rng-parse nxml-parse
rng-match rng-dt rng-util rng-pttrn nxml-ns nxml-mode nxml-outln
nxml-rap nxml-util nxml-glyph nxml-enc xmltok ruby-mode perl-mode
verilog-mode diff conf-mode make-mode tex-mode shell latexenc
org-element org-rmail org-mhe org-irc org-info org-gnus gnus-util
org-docview org-bibtex bibtex org-bbdb org-w3m org org-macro
org-footnote org-pcomplete pcomplete org-list org-faces org-entities
noutline outline org-version 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 format-spec cal-menu calendar cal-loaddefs
srecode/srt-mode semantic/analyze semantic/sort semantic/scope
semantic/analyze/fcn semantic/db semantic/format ezimage
srecode/template srecode/srt-wy semantic/wisent semantic/wisent/wisent
semantic/ctxt srecode/ctxt semantic/tag-ls semantic/find srecode/compile
srecode/dictionary srecode/table srecode eieio-base semantic/util-modes
semantic/util semantic semantic/tag semantic/lex cedet doc-view subr-x
jka-compr image-mode ps-mode add-log sh-script smie executable
find-dired dired semantic/fw mode-local find-func grep compile comint
ansi-color vc-mtn vc-hg vc-git diff-mode easy-mmode vc-bzr vc-src
vc-sccs vc-svn vc-cvs vc-rcs vc vc-dispatcher thingatpt etags xref
cl-seq ring eieio byte-opt bytecomp byte-compile cl-extra help-mode
easymenu cconv eieio-core cl-macs gv cl-loaddefs pcase cl-lib project
term/xterm xterm time-date disp-table mule-util tooltip eldoc electric
uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core frame 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 charscript case-table epa-hook jka-cmpr-hook help
simple abbrev minibuffer cl-preloaded 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
dbusbind inotify dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 4729592 517895)
 (symbols 48 40455 0)
 (miscs 40 112 310)
 (strings 32 292026 313931)
 (string-bytes 1 15565717)
 (vectors 16 275283)
 (vector-slots 8 2028489 240208)
 (floats 8 530 633)
 (intervals 56 977354 6401)
 (buffers 976 23)
 (heap 1024 235047 29774))