title: why eldoc mode makes emacs use 100% cpu?
body: <p>when i use eldoc,i add this to .emacs:</p>
  
  <pre><code> (add-hook 'emacs-lisp-mode-hook 'turn-on-eldoc-mode)
   (add-hook 'lisp-interaction-mode-hook 'turn-on-eldoc-mode)
   (add-hook 'ielm-mode-hook 'turn-on-eldoc-mode)
  </code></pre>
  
  <p>and then when i use emacs,the emacs will use 100% cpu and it stucks.
  but when i delete this code in .emacs,the emacs works.</p>
  
  <p>anyone has idea about this?Or how to debug the problem.</p>
  
  <p>Or anyother way to substitute for the eldoc mode</p>