bugGNU Octave - Bugs: bug #48296, demo hangs with subplot and pager


bug #48296: demo hangs with subplot and pager

Submitter:  Markus Mützel <mmuetzel>
Submitted:  Wed 22 Jun 2016 07:32:02 PM UTC
Category:  Plotting with OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Regression
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Wed 29 Jun 2016 08:06:35 PM UTC, comment #8: 

I pushed the patch on default for this specific bug. I agree that bug #47958 is probably related and should also be addressed.


Mike Miller <mtmiller>
Group Member
Mon 27 Jun 2016 05:58:53 PM UTC, comment #7: 

Lachlan, your patch fixes the hang on Ubuntu and Windows 10.

Markus Mützel <mmuetzel>
Group administrator
Mon 27 Jun 2016 02:39:40 AM UTC, comment #6: 

Here is a patch that implements Mike's workaround.

I can't reproduce the bug, and so I can't verify that the patch works.  Markus, could you please test it?

(file #37592)

Lachlan Andrew <lachlan>
Sun 26 Jun 2016 11:32:39 PM UTC, comment #5: 

Mike, as you say, turning paging off would be an effective workaround.

For the bug that turned paging on for ls and help, you raised several valid points (which I've addressed), and I agree that this is different issue.

My only concern with the workaround is that it doesn't fix the actual bug which I conjectured in comment #2 to be the same as is causing problems with entering debug mode with a partially completed plot.  That isn't a reason not to use the workaround in the meantime though.

Lachlan Andrew <lachlan>
Sun 26 Jun 2016 09:14:07 PM UTC, comment #4: 

Wouldn't an easy workaround be to page_screen_output(false, "local") in demo? This is already done in e.g. pkg list -forge, _run_test_suite_, and menu.

Lachlan, I know I argued against your patch proposal to turn on paging for a certain subset of commands, but I see a big difference between turning on paging when the user has requested it to be off, and turning paging off for one or two commands when the user wants it on because it would break something or cause confusion.

Mike Miller <mtmiller>
Group Member
Thu 23 Jun 2016 08:50:18 AM UTC, comment #3: 

@Lachlan: AFAIU operations involving drawing widgets can only be done in the main thread, so you can't separate the GUI and the graphics thread (see e.g. http://doc.qt.io/qt-4.8/thread-basics.html). All you can do is push time costly operations that don't involve drawing widgets in another thread.

Pantxo Diribarne <pantxo>
Group Member
Thu 23 Jun 2016 12:29:32 AM UTC, comment #2: 

I'd guess that this is caused by the same as bug #47598.

In both, there seems to be an incomplete figure drawn when keyboard input is requested.  In both, running without the GUI works.

Do you think it would be good to have the graphics drawn in a separate thread from the rest of the GUI?

Lachlan Andrew <lachlan>
Wed 22 Jun 2016 09:25:25 PM UTC, comment #1: 

I needed more '% comment' lines in the m-file in order to activate the pager.  I've attached test_hang2.m to the bug report.  I can reproduce this with

./run-octave -f
demo test_hang2

Also confirmed, the following works

./run-octave -f
more off
demo test_hang2

Finally, using qt, but not the GUI, also works

./run-octave -f --no-gui
demo test_hang2

(file #37553)

Rik <rik5>
Group administrator
Wed 22 Jun 2016 07:32:02 PM UTC, original submission:  

A demo that includes two vertically aligned subplots and that triggers the pager causes the GUI to hang.

I can reproduce that hang almost everytime on a freshly started Octave 4.1.0+ with "graphics_toolkit qt" on Ubuntu 16.04 and Windows 10. I cannot reproduce neither with fltk nor with gnuplot.
The demo runs fine on Octave 4.0.2.

Attached please find a minimal function that triggers that hang for me when running "demo test_hang". The command window has to have sufficiently few lines so that the demo triggers the pager.

Markus Mützel <mmuetzel>
Group administrator


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Attach Files:

Attached Files
file #37553:  test_hang2.m added by rik5 (520B - d2l/unknowntype)
file #37552:  test_hang.m added by mmuetzel (259B - text/x-objcsrc)


   bug dependencies.

Items that depend on this one: None found


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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2016-06-29 mtmiller StatusPatch Submitted Fixed
        Open/ClosedOpen Closed
    2016-06-27 lachlan Attached File- Added bug_48296_demo_pager.cset, #37592
        StatusConfirmed Patch Submitted
    2016-06-23 lachlan Dependencies- Depends on bugs #47958
    2016-06-22 rik5 Attached File- Added test_hang2.m, #37553
        StatusNone Confirmed
    2016-06-22 mmuetzel Attached File- Added test_hang.m, #37552

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