YComboBox addItem/addItems become very slow when the number of items is big

[anaselli]

I tested it with 2000 and i got it running after a while, qt and ncurses seem not to be affected.
I gave up waiting, with a bigger number (11821 items)

To test it patch ManyWidgets,cc as following:

diff --git a/examples/ManyWidgets.cc b/examples/ManyWidgets.cc
index 743def1..a7e3d92 100644
--- a/examples/ManyWidgets.cc
+++ b/examples/ManyWidgets.cc
@@ -298,9 +298,15 @@ int main( int argc, char **argv )
     cbox->setNotify( true );
     {
       YItemCollection items;
-      items.push_back( new YItem( "Item 1" ) );
-      items.push_back( new YItem( "Item 2" ) );
-      items.push_back( new YItem( "Item 3" ) );
+      for (int i=0; i<11822;i++)
+      {
+        std::stringstream str;
+        str << "Item " << i;
+        items.push_back( new YItem( str.str() ) );
+      }
+//       items.push_back( new YItem( "Item 1" ) );
+//       items.push_back( new YItem( "Item 2" ) );
+//       items.push_back( new YItem( "Item 3" ) );
       cbox->addItems( items ); // This is more efficient than repeatedly calling cbox->addItem
     }
     cbox               = YUI::widgetFactory()->createComboBox( atLeft(frame), "Editable:", true );

[mvidner]

I can reproduce the issue but unfortunately I cannot help much, because I don't know GTK.

From the libyui side, YSelectionWidget::addItems calls YSelectionWidget::addItem repeatedly, but also guards this with YWidget::startMultipleChanges and YWidget::doneMultipleChanges (via OptimizeChanges. Perhaps YGSELECTION_WIDGET_IMPL::addItem could take advantage of that.

[anaselli]

@mvidner i haven't understood if you mean to add start/end Multiple selection into gtk implementation or not, but i can confirm that adding that for the combobox widget defintely increase the performance.
qt is better in any cases, but with that trick now the program is usable

[mvidner]

No, I don't plan to fix it now. Go ahead, and mention here the patch that has helped.

[anaselli]

i didn't fix anything :) just used the xxxxMultipleChanges methods on combo:

diff --git a/examples/ManyWidgets.cc b/examples/ManyWidgets.cc
index 743def1..d645fe5 100644
--- a/examples/ManyWidgets.cc
+++ b/examples/ManyWidgets.cc
@@ -298,10 +298,15 @@ int main( int argc, char **argv )
     cbox->setNotify( true );
     {
       YItemCollection items;
-      items.push_back( new YItem( "Item 1" ) );
-      items.push_back( new YItem( "Item 2" ) );
-      items.push_back( new YItem( "Item 3" ) );
+      for (int i=0; i<11822;i++)
+      {
+         std::stringstream str;
+         str << "Item " << i;
+         items.push_back( new YItem( str.str() ) );
+      }
+      cbox->startMultipleChanges();
       cbox->addItems( items ); // This is more efficient than repeatedly calling cbox->addItem
+      cbox->doneMultipleChanges();
     }
     cbox               = YUI::widgetFactory()->createComboBox( atLeft(frame), "Editable:", true );
     cbox->setNotify( true );

[mvidner]

That is strange, I thought cbox->addItems already did call those.

[anaselli]

I see, but if you try my patch, you should easy verify what i mean :/

[ancorgs]

Since the Gtk backend is not developed or maintained by the YaST Team at SUSE, I'm adding the "other-maintainer" label to this in order to help filtering the various list of issues.