hugin-devs team mailing list archive

[Lukas Jirkovsky <792896@xxxxxxxxxxxxxxxxxx>]

I was able to identify two bugs plaguing the fast preview.

A first one is a hang in libpano math.c, line 297:
        while( *x_src >  var0 )
                *x_src -= 2 *  var0;
because *x_src = 2.17213129256892e+98 and var0 = 13652.608695652176. If my computations are correct, *x_src never changes because of the underflow. I'm able to reproduce this problem with one panorama in approximately one quarter of tests.

The other one is the same crash for which Terry already provided
backtrace using hellgrind. I was able to reproduce it twice, but after
adding some debug statements I was not able to reproduce it so far.

Atached is the gdb backtrace for both issues.

** Attachment added: "gdb"
   https://bugs.launchpad.net/hugin/+bug/792896/+attachment/2294159/+files/gdb

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https://bugs.launchpad.net/bugs/792896

Title:
  Fast Preview Hangs or Crashes since 2011.0

Status in Hugin - Panorama Tools GUI:
  Confirmed

Bug description:
  EDIT (August 6, 2011): summarized known information

  *WORKAROUND FOR USERS*: disable the Overview

  1- start Hugin
  2- load a project
  3- go to the Fast Preview Window.  don't touch anything else but described below as this could trigger the bug
  4- hit the button Show/Hide to hide the Overview
  5- quit Hugin
  Now Hugin should perform well.

  
  *AFFECTED SYSTEMS*

  - CPU: all systems with more than one thread, that is multi-core CPUs as well as single-core CPUs with hyperthreading.
  - Operating Systems: due to the different implementations of threading and OpenGL on different platform, some systems are more prone to error than others.  Mac OS X seems to be the least affected.  Windows seems to be the most affected.

  
  *AFFECTED VERSIONS*

  - All versions of Hugin since the introduction of the Overview in the Fast Preview are affected.  That is, all versions after revision 4808:8c577b320714 2011-01-09 12:21:18
  - This includes the final releases of 2011.0.0 as well as all beta/candidate releases of 2011.2.0

  
  *SUMMARY FOR DEVELOPERS / BUG HUNTERS*

  This is most likely a threading issue. Lukáš' hypothesis: "a race
  condition in OpenGL calls, when OGL is called by separate threads from
  both overview and fast preview. The reason is that OpenGL is not
  thread-safe and it can cause various problems when used within multi-
  threaded application."

  Run 'valgrind --tool=helgrind hugin' and try to reproduce the error to
  produce a useful backtrace like
  https://bugs.launchpad.net/hugin/+bug/792896/+attachment/2253077/+files
  /valgrind-out.txt

  
  *ORIGINAL BUG REPORT BELOW FOR COMPLETION:*

  Upgraded from 2010.4 to 2011.0.0 and it has hung 3 times in about 15
  sessions.  All three hangs happened while doing the same thing.....
  new session, load images, load a lens profile, set the canvas size
  (Calculate optimal size), save-as and save profile then click on GL
  (fast preview) button.  Fast preview window comes up, shows anchor
  image and then hangs.

  Is not reproducible.  Running 2011.0.0.0fd3e119979c built by Matthew
  Petroff on 64-bit Win7.

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