bugGNU Octave - Bugs: bug #59332, Variable Editor gets extremely...


bug #59332: Variable Editor gets extremely slow with large arrays

Submitted by:  Philip Nienhuis <philipnienhuis>
Submitted on:  Sat 24 Oct 2020 03:09:41 PM UTC  
Category:  GUI Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Performance
Status:  None Assigned to:  None
Originator Name:  Philip Nienhuis Open/Closed:  Open
Release:  dev Operating System:  Any

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Sat 24 Oct 2020 03:09:41 PM UTC, original submission:  

IMO the Variable Editor is a fantastic tool especially for debugging, however its usability is severely hampered when using it with large arrays.
AFAICS (but I may be wrong) the causes are:

  1. All cells of an array opened in the VE are re-rendered, even if only a very small part is visible in the pertinent array subpane;
  2. For each debug step, or return to the prompt, all variables open in the VE are re-rendered, also variables that haven't been touched at all between the last command prompts;
  3. Same applies when the VE pane or one of its subpanes is resized, or gets undocked.

Octave is almost completely inresponsive while the VE is being rendered; only the m-file Editor might respond to some actions.

Would it possible to only render cell ranges that are visible in and/or just outside the respective subpanes? I suppose it shouldn't be hard to find out what array cell ranges are displayed. All cell widths and -heights, subpane widhts and -heights and positions of subplane sliders, if any, are known. Maybe Qt even has ready-baked functions for it.

I guess that when 1. has been fixed, 2. and 3. become less relevant as far as performance goes. Obviously performance is usually second priority anyway during debugging; but it is demotivating to have to wait sometimes tens of seconds after each step before being able to proceed.

Philip Nienhuis <philipnienhuis>
Project Member


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