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Occasional Invalid Thread Access [message #1743438]

Thu, 15 September 2016 09:09

Eclipse User

Hi al,,

We're developing a small standalone RAP application.
We often encountered Invalid Thread Access that severely degrades our user experience. The error is still happening eventhough we wrap the ui updates to Display#sync/async like below:

		Display.getDefault().syncExec
		(
			new Runnable()
			{
				@Override
				public void run()
				{
					String message = "No record available";
					if (pagination != null)
					{
						if (pagination.getTotalRecordCount() > 0)
							message = MessageFormat.format("Page {0} of {1}", new Object[] { Integer.valueOf(pagination.getCurrentPage()), Integer.valueOf(pagination.getTotalPageCount()) });
					}

					AbstractTabularForm.this.lblPageNumber.setText(message);
				}
			}
		);

The error seems to be spreaded all over in our code, but above part is the most often.

Is there any other way we should do to prevent this error ?

Any help would be greatly appreciated.

Thanks & Regards,
Setya

Re: Occasional Invalid Thread Access [message #1743456 is a reply to message #1743438]

Thu, 15 September 2016 10:43

Eclipse User

Hi,
you should not call Display#getDefault as it can't be used outside UI thread, but provide a display instance outside background thread. Look also at RWT.getUISession().exec(Runnable).
HTH,
Ivan

Re: Occasional Invalid Thread Access [message #1743642 is a reply to message #1743456]

Sat, 17 September 2016 13:06

Eclipse User

Hi Ivan,

Thank you very much.

RWT.getUISession().exec(Runnable) seems to do the trick.

Regards,
Setya

Re: Occasional Invalid Thread Access [message #1743872 is a reply to message #1743642]

Tue, 20 September 2016 06:32

Eclipse User

"you should not call Display#getDefault as it can't be used outside UI thread"
Ivan, small question
If understood right Setya they want to update any form
AbstractTabularForm.this.lblPageNumber.setText(message);

read guide
"But when the UI needs to be updated, Display#asyncExec must be used, as it runs the code in the UI thread and thereby gives access to session scope and widgets."

Does RWT.getUISession().exec(Runnable) work well?

Re: Occasional Invalid Thread Access [message #1744031 is a reply to message #1743642]

Wed, 21 September 2016 10:34

Eclipse User

Hi Ivan,

The problem still happens and easily reproduced when user opens the same URL on 2nd browser tab or the 2nd instance of the same browser.

The error occurs at editor#dispose of the following code:

RWT.getUISession().exec
(
	new Runnable()
	{
		@Override
		public void run()
		{
			for (TableEditor tableEditor : DefaultColumnLabelProvider.this.TABLE_EDITORS)
			{
				final Control editor = tableEditor.getEditor();
							
				if (editor == null) continue;
						
				if (!editor.isDisposed())
					editor.dispose();
			}
		}
	}
);

I've also tried Display#syncExec w/ display instance from outside background thread. Nothing worked.

But the problem did not occur when user opens the 2nd same URL on different browser brand.

Thanks & Regards,
Setya

Re: Occasional Invalid Thread Access [message #1744087 is a reply to message #1744031]

Thu, 22 September 2016 05:38

Eclipse User

Hi,
class DefaultColumnLabelProvider is not RAP (JFace class). What is this filed DefaultColumnLabelProvider.this.TABLE_EDITORS? Is it static? Do you keep there all table editor instances from all UI sessions?
Regards,
Ivan

Re: Occasional Invalid Thread Access [message #1744105 is a reply to message #1744031]

Thu, 22 September 2016 07:07

Eclipse User

try so with async
Quote:

Display.getDefault().asyncExec(new Runnable() {
public void run() {
your_action_code
}
});

Re: Occasional Invalid Thread Access [message #1744146 is a reply to message #1744087]

Thu, 22 September 2016 13:28

Eclipse User

Hi Ivan,

DefaultColumnLabelProvider extends ColumnLabelProvider and I instantiate this class for each table column that I use. TABLE_EDITORS is a final non-static field in DefaultColumnLabelProvider.

I use TABLE_EDITORS to contain all table editors created so that I can dispose them later when I rebuild the table items.

Finally I configure the form that contains this table in Spring using session scope.

Thanks & Regards,
Setya

Re: Occasional Invalid Thread Access [message #1744149 is a reply to message #1744105]

Thu, 22 September 2016 13:55

Eclipse User

Hi Dmitry,

Thank you for your suggestion.

The error indeed gone, but new problem arises, where app in the 1st tab does not get updated properly every time there's UI updates.

Should I block user from opening the same app on the same session ?

Thanks & Regards,
Setya

Re: Occasional Invalid Thread Access [message #1744151 is a reply to message #1744149]

Thu, 22 September 2016 16:00

Eclipse User

>where app in the 1st tab does not get updated properly every time there's UI updates.
use thread and put inside method "run" your code with sleep for every time. don't forget set condition for stop thread

>Should I block user from opening the same app on the same session ?
Why?

[Updated on: Thu, 22 September 2016 16:02] by Moderator

Re: Occasional Invalid Thread Access [message #1744301 is a reply to message #1744151]

Sat, 24 September 2016 07:33

Eclipse User

Hi Dmitry,

Quote:

Should I block user from opening the same app on the same session ?
Why?

Since I configure the application in Spring bean using 'session' scope and it seems that all this problem occurs when application is shared with the same session.

I was wondering how other RAP applications handle this situation.

Thanks & Regards,
Setya

Re: Occasional Invalid Thread Access [message #1744326 is a reply to message #1744301]

Sun, 25 September 2016 10:29

Eclipse User

I didn't deep dive to RAP but sessions works stable. New browser-tab is new UI-session .

Re: Occasional Invalid Thread Access [message #1744330 is a reply to message #1744326]

Sun, 25 September 2016 14:26

Eclipse User

Hi Dmitry,

It seems that for every browser tab I have to limit the scope to RAP's UISession scope so that each tab will get it's own instance. I've found this which I'll give a try.

Regards,
Setya

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