Cancelling a DataTableVisualPropertiesDialog may take very long and block GUI

[bburlacu]

The DataTableVisualPropertiesDialog saves the original visual properties for each row and restores them in the event handler for the dialog cancel button.

This causes each series to be redrawn in the Row_VisualPropertiesChanged event handler of the DataTableView. Inside, the DataPointCollection for each series is cleared, which causes performance problems [1], [2].

On a series with ~7000 points, the clear operation took 32s on my machine. In total, canceling the dialog blocks the HeuristicLab GUI for approximately 2 minutes.

This problem can be alleviated by implementing the fix suggested in [1], which reduces the blocking time from 2min to a few seconds on the tested data.

In the future, it might be useful to consider a different mechanism for updating/restoring row visual properties.

[1 ] ​https://stackoverflow.com/questions/5744930/datapointcollection-clear-performance

[2 ] ​https://connect.microsoft.com/VisualStudio/feedback/details/596212/performance-problem-in-mschart-datapointcollection-clear

[bburlacu]

r15619: Performance improvement in DataTableView

[abeham]

As there is a trunk commit in this ticket, the version should be set to trunk.

[pfleck]

Tested r15619 and GUI reactiveness is noticeable better with the change.

Code looks fine. But, I do not understand why a loop with a RemoveAt is used instead of a simple Clear. I tried a Clear and seems equally fast. Additionally, I looked at the source and both RemoveAt and Clear seem to be forwarded to a List<T>.RemoveAt and List<T>.Clear. Therefore I think we should use a simple Clear. Please check if this does not have other effects I did not notice when using Clear.

[bburlacu]

data point collection performance bug

[bburlacu]

This workaround was used to avoid a performance bug referenced here: ​https://stackoverflow.com/questions/5744930/datapointcollection-clear-performance

Unfortunately in the mean time the MSDN link has disappeared, but in my tests simply using Clear is much slower. Using 50k points, I get:

• ClearPoints method: 0.004 s
• Clear method: 0.837 s

I've attached an HL script which illustrates this behavior.

[pfleck]

It seems that the ScatterPlotView has the same issue with the .Clear() calls. I guess they can be fixed in the same manner.

Can you also look for other places where your improvement could be applied?

[gkronber]

Let's release the fix r15619 and close this ticket. We can create a new ticket for ScatterPlotView.

Since r15619 has been reviewed already, can we set the status of this ticket to "Ready to release" and merge to stable?

[mkommend]

r17056: Merged r15619 into stable.