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Revision as of 21:24, 24 February 2014
Summary
Gonzalo Odiard and Manuel Quiñones did a hackaton to find out why the lists that contain icons are so slow. The affected views in Sugar are the Journal list and the activities list. This feature is about improving the TreeView performance.
Owner
- Name: Manuel Quiñones
- Name: Gonzalo Odiard
Current status
- Targeted release: 0.102
- Last updated: Feb 24, 2014
- Percentage of completion: 60%
Detailed Description
Findings
- The source of the performance issues is Sugar CellRendererIcon, a treeview without it works ok. https://github.com/sugarlabs/sugar-toolkit-gtk3/blob/master/src/sugar3/graphics/icon.py#L781
- Sugar CellRendererIcon has too much logic inside. It should only handle how to render itself.
- Sugar CellRendererIcon is connected to many signals. Just detaching them while scrolling provides a performance boost.
- Sugar CellRendererIcon could benefit from caching values instead of calculating them on each render.
We couldn't find what's wrong with the Journal. We guess there is a DBus blocking call, but we could't confirm that.
GTK+ concepts
- GtkTreeView — A widget for displaying both trees and lists https://developer.gnome.org/gtk3/stable/GtkTreeView
- GtkTreeViewColumn — A visible column in a GtkTreeView widget https://developer.gnome.org/gtk3/stable/GtkTreeViewColumn.html
- GtkCellRenderer — An object for rendering a single cell https://developer.gnome.org/gtk3/stable/GtkCellRenderer
Benefit to Sugar
Performance!
Scope
Affects Shell and Toolkit.
UI Design
We should not regress treeviews. Pay special attention to Journal list and activities list.
How To Test
We did a test program that has a list (treeview) with many rows. Each row has a cellrenderer icon. The program automatically starts scrolling until the end of the list is reached. Then we can get profiling information using Python cProfile http://docs.python.org/2/library/profile.html . We ran the test like this inside a Sugar shell:
python -m cProfile test_treeview.py > profile.txt
User Experience
Users should notice a performance boost.
Dependencies
No deps.
Contingency Plan
These optimizations can come in small steps, so there is no need for a contingency plan.
Documentation
To be written.
Release Notes
To be written.
Comments and Discussion
Your comments are very welcome. Please discuss through the mailing list.