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| Re: Memory consumption of virtual TableViewers [message #333722 is a reply to message #333721] |
Mon, 29 December 2008 10:51   |
 Thomas Schindl
Messages: 6651
Registered: July 2009 |
Senior Member |
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Hi David,
Short answer - no. Virtual only means that the items are not created at
once but only when they are scrolled into view but they won't get
collected once they are scrolled out of view.
Maybe something like a paging table could solve this issue.
Tom
David Pérez schrieb:
> Hi all,
>
> I have in my app a virtual TableViewer (SWT.VIRTUAL) that shows a lot of
> items.
> My custom ILazyContentProvider doesn't maintain all the items, it
> fetches on the fly from a database as needed.
>
> Theorically the memory consumption of my app would be very low,
> independent from the number of rows.
>
> But empirically, the memory consumption increases a lot as the number of
> rows increases. I have investigated a little with the MAT tool
> (http://www.eclipse.org/mat/), and I get that the TableViewer component
> is holding for a TableViewer with 15403 rows this numbers:
>
> 15403 org.eclipse.swt.widgets.TableItem's which holds 6 Mb of memory
> 23006 int[]'s
> 40325 String's with over 2 Mb memory
> ...
>
> I need to display over 1,000,000 rows, so TableViewer's aren't scalable.
>
> Is it possible to optimize the memory somehow?
> Thanks in advance for any valuable tip.
>
>
--
B e s t S o l u t i o n . at
------------------------------------------------------------ --------
Tom Schindl JFace-Committer
------------------------------------------------------------ --------
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| Re: Memory consumption of virtual TableViewers [message #333723 is a reply to message #333721] |
Mon, 29 December 2008 10:58 |
David Pérez
Messages: 228
Registered: July 2009 |
Senior Member |
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Further investigation:
public class Table {
TableItem [] items; // <--- This is the guilty of memory excesive use
....
// This is where the items are created and never released....
TableItem _getItem (int index) {
if ((style & SWT.VIRTUAL) == 0) return items [index];
if (items [index] != null) return items [index];
return items [index] = new TableItem (this, SWT.NONE, -1, false);
}
}
Maybe this is a topic for the SWT newsgroup.
I'll post there.
David Pérez wrote:
> Hi all,
> I have in my app a virtual TableViewer (SWT.VIRTUAL) that shows a lot of
> items.
> My custom ILazyContentProvider doesn't maintain all the items, it fetches
> on the fly from a database as needed.
> Theorically the memory consumption of my app would be very low,
> independent from the number of rows.
> But empirically, the memory consumption increases a lot as the number of
> rows increases. I have investigated a little with the MAT tool
> (http://www.eclipse.org/mat/), and I get that the TableViewer component is
> holding for a TableViewer with 15403 rows this numbers:
> 15403 org.eclipse.swt.widgets.TableItem's which holds 6 Mb of memory
> 23006 int[]'s
> 40325 String's with over 2 Mb memory
> ....
> I need to display over 1,000,000 rows, so TableViewer's aren't scalable.
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| Re: Memory consumption of virtual TableViewers [message #333730 is a reply to message #333724] |
Tue, 30 December 2008 09:09 |
David Pérez
Messages: 228
Registered: July 2009 |
Senior Member |
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Here is my solution that works:
public class PagedTable extends Table {
int[] selectedIndices;
public PagedTable(Composite parent, int style) {
super(parent, style | SWT.VIRTUAL);
}
private void freeUnusedItems(Widget ignoreItem) {
if (items.length > 0) {
int[] range = getVisibleRange();
selectedIndices = getSelectionIndices();
for (int i = 0; i < range[0]; i++) {
releaseItem(i, ignoreItem);
}
for (int i = range[1]+1; i < items.length; i++) {
releaseItem(i, ignoreItem);
}
}
}
private void releaseItem(int i, Widget ignoreItem) {
if (items[i] != null && items[i] != ignoreItem) {
for (int j = 0; j < selectedIndices.length; j++) {
// No liberar elementos seleccionados
if (selectedIndices[j] == i) {
return;
}
}
if (!items[i].isDisposed()) {
items[i].release(false);
}
items[i] = null;
}
}
public int[] getVisibleRange() {
int[] res = new int[2];
int height = getItemHeight();
int totalHeight = getSize().y;
if (getHeaderVisible()) {
totalHeight -= getHeaderHeight();
}
res[0] = getTopIndex();
res[1] = res[0]+(totalHeight+height-1)/height-1;
return res;
}
@Override TableItem _getItem(int index) {
TableItem res = super._getItem(index);
freeUnusedItems(res);
return res;
}
@Override void postEvent(int eventType, Event event) {
super.postEvent(eventType, event);
if (eventType == SWT.SELECTED) {
freeUnusedItems(event.item);
}
}
}
This class must be placed in the existing org.eclipse.swt plugin, as
Eclipse doesn't ease the expandibility of builtin classes in any other way.
I hope this will be useful to someone else.
David Pérez wrote:
> Thanks Tom for your quick answer. :-)
> Do you consider is it easy to implement such a paging table?
> Does anybody know a Table replacement?
> Tom Schindl wrote:
>> Hi David,
>> Short answer - no. Virtual only means that the items are not created at
>> once but only when they are scrolled into view but they won't get
>> collected once they are scrolled out of view.
>> Maybe something like a paging table could solve this issue.
>> Tom
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