Loading data into NewTable is slowing down scrolling and other interaction

[aneeskA]

This is how I am creating the table

topicMessages := [][]string{}
messageList := widget.NewTable(
		func() (int, int) {
			return len(topicMessages), 2
		},
		func() fyne.CanvasObject {
			label := widget.NewLabel("")
			label.Truncation = fyne.TextTruncateEllipsis
			return label
		},
		func(i widget.TableCellID, o fyne.CanvasObject) {
			o.(*widget.Label).SetText(topicMessages[i.Row][i.Col])
		},
	)

and to update the rows, I listen to a kafka topic and add each message into the the topicMessages array.

*messages = append(*messages, []string{msg.Timestamp.Format("2006-01-02 15:04:05"), string(msg.Value)})

Please watch the video to see the behaviour when I load data into it. Scrolling takes a while to respond after I stopped loading data.

https://youtu.be/3h7Jz1TpypU

~76K rows in total.

Can I get some guideline on how to deal with this usecase?

[aneeskA]

Also here,

I can see that the Messages column contain Timestamp data. I am also not sure if this is a UI update problem or my code issue.

[aneeskA]

If it helps, I am on

fyne.io/fyne/v2 v2.4.6-0.20240610054136-832fe62264a4

[andydotxyz]

Just adding items to the data won't make anything change on the UI, you'll need to share what code is being executed on the Fyne side to understand where slowdown might occur.

[aneeskA]

There is no activity other than loading the data to Table. The code that I attached about is all that I am doing. I read from a Kafka topic, and show the message in the Table. The table has 3 column - a row counter, timestamp and message itself.

After loading about 3k rows also I am seeing the slowness of scrolling.

This is how I set the headers

messageList.UpdateHeader = func(id widget.TableCellID, o fyne.CanvasObject) {
		switch id.Col {
		case -1:
			o.(*widget.Label).TextStyle = fyne.TextStyle{Bold: false}
			o.(*widget.Label).SetText(strconv.Itoa(id.Row + 1))
		case 0:
			o.(*widget.Label).SetText("Timestamp")
		case 1:
			o.(*widget.Label).SetText("Message")
		}
	}

[andydotxyz]

The number of rows in a list should not impact its speed as we only render what is visible. And adding more rows should have no impact at all on speed because if the new rows are not visible all it does is make the scrollbar shorter.

Is it possible that your data access is slow somehow, or that you are continually calling refresh in some other place?

It might be worth profiling your code to see where the CPU is spinning, because it should not be in the Table rendering.

[andydotxyz]

The only thing I can think of is maybe around the row where it starts to be slow the cell has a massive data value that you're loading into the label?

[aneeskA]

All the rows have the same set of data. I am not calling Refresh() anywhere - double checked. But I do call ScrollToBottom() so that the latest row is always visible to the user. I will profile and report back. Thanks a lot for your pointers.