Live preview doesn't work after updating the values many times (timeout reached)

[Masato HASHIMOTO]

In Draw From Triangle extension, while turning on and off some common objects many times with live preview, all common objects disappeared and cannot apply anymore.

Steps to reproduce:
1) Draw a triangle by path tool.
2) Call Draw From Triangle extension.
3) Turn on the live preview mode and turn on and off some common objects many times.

Actual result:
All previewed objects disappeared (If you are (un)lucky) and cannot preview and apply anymore after that.

Inkscape version: trunk-r22256
locale: ja_JP.UTF-8
Build & Platform: Build 2009-09-19 on Arch Linux (x86_64)

Attached file:
SVG file, gdb log and xsession-errors (Note: While taking these logs, this issue occurred **3 times**)

[Alvin Penner (apenner)]

- cannot duplicate this problem on Windows XP, Inkscape build 0.47pre2.
- I turned on and off the object 'incircle' 10 times will no ill effects.
- just for curiosity, which version of Python?
- mine is Python 2.5.1 and libgdkmm-2.4-1.dll

[su_v (suv-lp)]

Did you use any functions/custom points from the second tab? As explained on the help page, some may result in 'division-by-zero' - I don't know if Python then is supposed to quit or how this is handled when Python is called by Inkscape…

I did see some related console messages like

  ** (inkscape-bin:24962): CRITICAL **: int Inkscape::Extension::Implementation::Script::execute(const std::list<std::string, std::allocator<std::string> >&, const std::list<std::string, std::allocator<std::string> >&, const Glib::ustring&, Inkscape::Extension::Implementation::Script::file_listener&): assertion `in_command.size() > 0' failed

and at one time several repeated

  Can't Spawn!!! spawn returns: 19

but can't yet reproduce it consistently. No disfunctional preview either…

[su_v (suv-lp)]

forgot: Inkscape 0.46+devel r22268 custom on OS X 10.5.8, Python 2.6.2

[Masato HASHIMOTO (hashimo)]

Alvin Penner :
Mine is Python 2.6.2 with some patches (http://repos.archlinux.org/viewvc.cgi/python/repos/extra-x86_64/)

~suv:
> Did you use any functions/custom points from the second tab?

No, I don't touch the tab as default.

[jazzynico (jazzynico)]

Not reproduced on Ubuntu 11.04, trunk revision 10610.

Are you still affected with recent inkscape versions?

[Masato HASHIMOTO (hashimo)]

This still reproduced on trunk-r10610.
I recorded it. Please watch attached movie.
If "affect" means that I'm in trouble by this issue, answer is No :)

[jazzynico (jazzynico)]

Thanks for the record!
I've tried to check/uncheck everything 5 times with no issue, but I remember having noticed it with other extensions, when changing lots of things in live preview. Maybe not related to this extensions but to the extension system.

[jazzynico (jazzynico)]

Ah, yes, it was when debugging new extensions. But I was live editing the python script while testing in Inkscape (without restarting it)...

[jazzynico (jazzynico)]

Tested again with Debian testing Inkscape trunk revision 12010, but I still can't reproduce the bug.

[jazzynico (jazzynico)]

Just ran into the same issue while testing a new extension. But I still can't find clear steps to reproduce it...

[jazzynico (jazzynico)]

The bug is due to the extension system that unloads the extension when an expiration timer is reached (after 240 seconds). Applying the extension resets the timer, but using the live preview not.
Of course, closing the extension and reopening it resets the timer as well.

[jazzynico (jazzynico)]

The attached patch should reload the extension is its timer has expired while the live preview is still active.
Tested successfully on Crunchbang Waldorf, Inkscape trunk revision 13425.

[jazzynico (jazzynico)]

Timout reduced to 10 seconds (instead of 240) to help testing (not to be committed!)

[jazzynico (jazzynico)]

Fixed revision 13430.