Re: [ROOT] TGListBox/TList/MapSubwindows() timing issues

From: Fons Rademakers (Fons.Rademakers@cern.ch)
Date: Tue Aug 14 2001 - 14:41:01 MEST


Hi Mark,

  could you send me the app so I can investuaget this.

Cheers, Fons.



Mark Thomson wrote:
> 
> Dear Rooters,
> 
> I have written a simple GUI application to log error messages based
> on the TGListBox class. I allow for upto 1000 entries. After 1000 entries,
> all new entries result in the first entry being deleted
>             TGListBox->RemoveEntry(id);
> and the new entry being added to the end of the list
>             TGListBox->AddEntry(pListBoxTextEntry,pLayout);
> 
> This works well and can cope with high message rates ( ~100 Hz ) until
> 1000 entries have been filled. After this messages can only be logged
> at ~4 Hz. The bottleneck occurs in TGListBox::MapSubwindows()
> 
> It is somehow connected to removing objects from the TList in the
> listbox container.
> 
> I've tried to investigate the causes and find that if I remove the
> last entry rather than the first entry of the list then rate problems
> go away. It seems that calling fListBox->MapSubwindows() after removing
> the first entry in the list burns CPU.
> 
> One final piece of information, if the screen is iconized the rate
> problems also go away.
> 
> I'm using Root V03_01_06 on a 750 MHz pc running Linux.
> 
>             Any suggestions ?
>                    cheers,
>                      Mark Thomson

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