title: Emacs: ac-slime for auto complete
body: <p>I am trying to add auto complete for *.lisp files. My slime setting is:</p>
  
  <pre><code>(add-to-list 'load-path "~/.emacs.d/plugins/slime/")
  (setq slime-lisp-implementations
        '((sbcl ("/opt/sbcl/bin/sbcl" "--core" "/opt/sbcl/lib/sbcl/sbcl.core")
                :coding-system utf-8-unix
                :env ("SBCL_HOME=/opt/sbcl/lib/sbcl"))
          (ccl ("/opt/ccl/lx86cl64")
               :coding-system utf-8-unix)))
  (require 'slime-autoloads)
  (slime-setup '(slime-fancy))
  </code></pre>
  
  <p>And ac-slime setting is:</p>
  
  <pre><code>(require 'ac-slime)
  (add-hook 'slime-mode-hook 'set-up-slime-ac)
  (add-hook 'slime-repl-mode-hook 'set-up-slime-ac)
  (eval-after-load "auto-complete"
    '(add-to-list 'ac-modes 'slime-repl-mode))
  </code></pre>
  
  <p>Each time I type a word in *.lisp file, auto complete popups some candidates but after a second minibuffer outputs</p>
  
  <pre><code>error in process filter: Reply to canceled synchronous eval request 
  tag=slime-result-6-19579 
  sexp=(swank:simple-completions "de" (quote "COMMON-LISP-USER"))
  </code></pre>
  
  <p>and the popup stuck for a while. After that I can continue my selection.</p>
  
  <p>My question is how to remove this error and stuck? Any help is appreciated. </p>