[Bug 628657] Re: freezes for > 10s when displaying long changelogs

[Tormod Volden]

This is bad as ever on 14.04. The current kernel updates have a > 10000
line changelog, and update-manager freezes around 20 seconds (on a quad-
core, 8 GB RAM desktop) before it refreshes the GUI when I click on
these packages.

I use the attached patch as a stop gap, it only lists up to 24 lines of
a changelog. A real fix is probably a bit more complex because of the
convoluted way the changelog is filtered and displayed. Maybe python
cannot do it efficiently enough, the match operations seem pretty slow
and limited and processing only line by line with all the hoops to get
the work done doesn't help.

The patch can be applied with: sudo patch /usr/lib/python3/dist-
packages/UpdateManager/UpdatesAvailable.py < update-manager-changelog-
slow-628657.patch

** Patch added: "stop gap measure, for irritation relief"
   https://bugs.launchpad.net/ubuntu/+source/update-manager/+bug/628657/+attachment/4178830/+files/update-manager-changelog-slow-628657.patch

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https://bugs.launchpad.net/bugs/628657

Title:
  freezes for > 10s when displaying long changelogs

Status in “update-manager” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: update-manager

  There are a bunch of openoffice packages in proposed right now. When
  selecting on of these in update-manager (does not matter if I have
  "Description of update" open or not) the GUI freezes and the CPU goes
  high for 10 seconds while "Downloading list of changes" is displayed.
  If I click a non-oo package the response is immediate. Selecting the
  same oo package again causes the same freeze/CPU churn.

  I do not know how to trace a pile of python, but find enclosed a
  ltrace in case it can cast some light over it.

  When I ran ltrace -c on it, the one click caused 6 minutes of waiting yielding these results:
  % time     seconds  usecs/call     calls      function
  ------ ----------- ----------- --------- --------------------
   15.23   85.527228         186    459799 free
   15.13   84.985249         161    525668 memcpy
   12.31   69.140534         142    485820 memset
   10.55   59.279684         141    419911 malloc
    8.67   48.723256         211    230058 strchr

  plz rewrite update-manager in c thx bye :-P

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: update-manager 1:0.134.10
  ProcVersionSignature: Ubuntu 2.6.32-24.41-generic 2.6.32.15+drm33.5
  Uname: Linux 2.6.32-24-generic i686
  Architecture: i386
  Date: Thu Sep  2 08:57:19 2010
  ExecutablePath: /usr/bin/update-manager
  InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
  InterpreterPath: /usr/bin/python2.6
  PackageArchitecture: all
  ProcEnviron:
   PATH=(custom, user)
   LANG=en_US.utf8
   SHELL=/bin/bash
  SourcePackage: update-manager

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