bug#22305: 24.5; permanent 100% CPU load for no apparent reason

["Roland Winkler" <winkler@gnu.org>]

Lately emacs gives me some strange problem, where according to `top'
the CPU load due to the emacs process goes up to a permanent value
of 100% (and I notice this because the laptop fan starts spinning
loudly), whereas according to `ps' the emacs process continues to
give rise to only a marginal CPU load.  While this happens, emacs
responds normally, so it appears that emacs is not trying to do
anything unusual in the background.

I did not have this problem while I was using emacs 24.5 under
ubuntu 14.04.  It only appeared lately when I upgraded to a new
laptop running ubuntu 15.10.  I am not aware of any significant
change in my emacs configuration since I made this switch.

What can I do to pin this down further?  So far, I have not noticed
anything that triggers this behavior reproducibly and my workaround
has been to restart emacs.  But that's not nice for a recurring
problem (about once per day).



In GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.7)
 of 2015-11-24 on regnitz
Windowing system distributor `The X.Org Foundation', version 11.0.11702000
System Description:	Ubuntu 15.10

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.utf8
  value of $XMODIFIERS: 
  locale-coding-system: utf-8-unix