When I try run describe-variable on package-archive-contents C-h v package-archive-contents emacs hangs. It hangs at least 5 minutes, maybe forever (I did not wait any longer).

Seems like Esc : (print package-archive-contents) also almost hangs.. It outputs an enormous string to message buffer after a minute. When trying to copy the string to the clipboard emacs hangs again..

I am running Emacs version 25.1 on Ubuntu 16.10.

Running C-h v package-archives gives current value:

 (("gnu" . "http://elpa.gnu.org/packages/") ("marmalade"
 . "http://marmalade-repo.org/packages/") ("melpa"
 . "http://melpa.milkbox.net/packages/") ("org"
 . "http://orgmode.org/elpa/"))
  • package-archive-contents contains meta-information about all versions of all packages in all archives. That's a huge amount of data; printing all of it naturally takes quite some time.
    – user227
    Oct 25 '16 at 10:44
  • 1
    @lunaryorn Agree. But I was only trying to get the documentation for the variable: C-h v package-archive-contents. It should not try to print the variable (if it is large) when a user tries to get the documentation Oct 25 '16 at 11:02
  • I see. I guess you need to report that as a bug
    – user227
    Oct 25 '16 at 21:35

To debug Emacs, it's always best to start a new instance with the -q option. This opens Emacs without loading an init file. You can then start investigating with the C-h v and C-h f commands which open documentation for variables and functions, respectively.

It looks like package-archive-contents is not part of base Emacs, but rather package.el. Execute (require 'package) to load it. Once package.el has been loaded, the documentation for variable package-archive-contents reads as:

package-archive-contents is a variable defined in ‘package.el’.
Its value is nil.

  This variable may be risky if used as a file-local variable.

Cache of the contents of the Emacs Lisp Package Archive.
This is an alist mapping package names (symbols) to
non-empty lists of ‘package-desc’ structures.

The cache of the Emacs Lisp Package Archive may be quite large. In the case of Emacs being opened with -q, only elpa will be cached. To do this, run (package-initialize). Now the documentation for package-archive-contents will take longer to load. It took several minutes for me. This is because the value is no longer nil. The value is 1000+ lines of information. Consider that in your case, you have the additional archives of melpa and marmalade.

  • It should be faster in Emacs 26, for earlier versions, indenting lisp was quadratic in the number of lines of the expression being indented (see Bug#25122).
    – npostavs
    Jan 29 '18 at 2:50

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