Home » Modeling » EMF "Technology" (Ecore Tools, EMFatic, etc) » [EMF Client Platform] Modifying content of ECPProject in non-UI thread
| [EMF Client Platform] Modifying content of ECPProject in non-UI thread [message #1142797] |
Thu, 17 October 2013 21:35  |
 Steffen Lehnert
Messages: 22
Registered: October 2013 |
Junior Member |
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Hi,
I am using an ECP application which I extended with some custom UI features and the underlying code.
I added a few custom commands and handlers to perform the required operations on a project selected by the user in his/her model explorer.
Since most of these operations are long-running operations, I encapsulated them in ProgressMonitors to prevent the UI thread from starving and to illustrate the progress of the operation to the user.
My problem is that I'm running into "java.util.ConcurrentModificationExceptions" whenever one of the ProgressMonitor-operations modifies the content of an ECPProject, since the operation is executed in a thread other than the UI thread:
MyOperation op = new MyOperation(project);
ProgressMonitorDialog progressDialog = new ProgressMonitorDialog(shell);
progressDialog.run(true /*fork, run in separate thread*/, false, op);
No exception is thrown when the operation is executed within the UI thread, but then the UI thread may become inresponsive until the operation is complete, which of course is not surprising:
MyOperation op = new MyOperation(project);
ProgressMonitorDialog progressDialog = new ProgressMonitorDialog(shell);
progressDialog.run(false /*do not fork, run in UI thread*/, false, op);
How can I modify the content of an ECPProject in a thread other than the UI thread without running into synchronization errors?
Any help would be appreciated as I'm not really into UI programming with Eclipse/SWT/ECP!
Cheers,
Steffen
Below my post you can find a very simple example that illustrates my problem:
// a simple handler:
public class MyHandler extends AbstractHandler
{
public Object execute(ExecutionEvent event) throws ExecutionException
{
ISelection sel = HandlerUtil.getCurrentSelection(event);
final ECPProject project = (ECPProject) ((StructuredSelection) sel).getFirstElement();
final Shell shell = HandlerUtil.getActiveWorkbenchWindow(event).getShell();
try
{
MyOperation op = new MyOperation(project);
ProgressMonitorDialog progressDialog = new ProgressMonitorDialog(shell);
progressDialog.run(true, false, op);
}
catch (InvocationTargetException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (InterruptedException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
// a simple operation encapsulated in a ProgressMonitor:
public class MyOperation implements IRunnableWithProgress
{
private ECPProject project;
public MyOperation(ECPProject newProject)
{
project = newProject;
}
@Override
public void run(final IProgressMonitor monitor) throws InvocationTargetException, InterruptedException
{
monitor.beginTask("Add some elements to the project", 1000);
for(int i = 0; i < 1000; i++)
{
project.getContents().add( MyModelFactory.eINSTANCE.createMyModel() );
monitor.worked(1);
}
monitor.done();
}
}
[Updated on: Thu, 17 October 2013 21:38] Report message to a moderator |
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| Re: [EMF Client Platform] Modifying content of ECPProject in non-UI thread [message #1143903 is a reply to message #1142797] |
Fri, 18 October 2013 13:57  |
Eugen Neufeld
Messages: 63
Registered: March 2012 |
Member |
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Hi Steffen,
thank you for posting this problem.
You would extremly help us by providing a stacktrace of this issue.
Cheers,
Eugen
Am 17.10.2013 23:35, schrieb Steffen Lehnert:
> Hi,
>
> I am using an ECP application which I extended with some custom UI
> features and the underlying code.
> I added a few custom commands and handlers to perform the required
> operations on a project selected by the user in his/her model explorer.
>
> Since most of these operations are long-running operations, I
> encapsulated them in ProgressMonitors to prevent the UI thread from
> starving and to illustrate the progress of the operation to the user.
>
> My problem is that I'm running into
> "java.util.ConcurrentModificationExceptions" whenever one of the
> ProgressMonitor-operations modifies the content of an ECPProject, since
> the operation is executed in a thread other than the UI thread:
>
> MyOperation op = new MyOperation(project);
> ProgressMonitorDialog progressDialog = new ProgressMonitorDialog(shell);
> progressDialog.run(true /*fork, run in separate thread*/, false, op);
>
> No exception is thrown when the operation is executed within the UI
> thread, but then the UI thread may become inresponsive until the
> operation is complete, which of course is not surprising:
>
> MyOperation op = new MyOperation(project);
> ProgressMonitorDialog progressDialog = new ProgressMonitorDialog(shell);
> progressDialog.run(false /*do not fork, run in UI thread*/, false, op);
>
> How can I modify the content of an ECPProject in a thread other than the
> UI thread without running into synchronization errors?
> Any help would be appreciated!
>
> Cheers,
> Steffen
>
> Below my post you can find a very simple example of a custom handler and
> the corresponding operation that will throw the
> "java.util.ConcurrentModificationExceptions" as "fork" is set to "true":
>
>
> // a simple handler:
> public class MyHandler extends AbstractHandler {
> public Object execute(ExecutionEvent event) throws
> ExecutionException {
> ISelection sel = HandlerUtil.getCurrentSelection(event);
> final ECPProject project = (ECPProject) ((StructuredSelection)
> sel).getFirstElement(); final Shell shell =
> HandlerUtil.getActiveWorkbenchWindow(event).getShell();
> try
> {
> MyOperation op = new MyOperation(project);
> ProgressMonitorDialog progressDialog = new
> ProgressMonitorDialog(shell);
> progressDialog.run(true, false, op);
> }
> catch (InvocationTargetException e)
> {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
> catch (InterruptedException e)
> {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
>
> return null;
> }
> }
>
> // a simple operation encapsulated in a ProgressMonitor:
> public class MyOperation implements IRunnableWithProgress
> {
> private ECPProject project;
> public MyOperation(ECPProject newProject)
> {
> project = newProject;
> }
> @Override
> public void run(final IProgressMonitor monitor) throws
> InvocationTargetException, InterruptedException
> { monitor.beginTask("Add some elements to the project", 1000);
>
> for(int i = 0; i < 1000; i++)
> {
> project.getContents().add(
> MyModelFactory.eINSTANCE.createMyModel() ); monitor.worked(1);
> }
>
> monitor.done();
> }
> }
>
--
Eugen Neufeld
Get Professional Eclipse Support: http://eclipsesource.com/munich
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| Re: [EMF Client Platform] Modifying content of ECPProject in non-UI thread [message #1153205 is a reply to message #1144034] |
Thu, 24 October 2013 12:52 |
Eugen Neufeld
Messages: 63
Registered: March 2012 |
Member |
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Hi Steffen,
the issue is more cumbersome then we thought.
We are about to fix this.
But we won't create a hotfix release for this.
The fix will be in the 1.1.0 release which will be on Tuesday next week.
Cheers,
Eugen
--
Eugen Neufeld
Get Professional Eclipse Support: http://eclipsesource.com/munich
Am 18.10.2013 17:49, schrieb Eugen Neufeld:
> Hi Steffen,
> thank you for the stacktrace.
> I think I know what causes the exception.
> I will check and fix it next week. So there will be a hotfix release
> next week.
> I will notify you as soon as we have the release.
>
> Cheers,
> Eugen
>
> Am 18.10.2013 17:19, schrieb Steffen Lehnert:
>> Hi Eugen,
>>
>> please find attached the stacktrace when executing the handler.
>> I started a new ECP application with an empty workspace and created a
>> new project ("Test") for this test.
>>
>> Regards,
>> Steffen
>>
>>
>> p.s.:
>> I've noticed this behavior after upgrading from EMFStore/ECP 0.9.3 to
>> the recent version (1.0.3).
>> Previously, I wrapped all project-modifying operations with
>> "EMFStoreCommand" like this:
>>
>> // handler code...
>>
>> new EMFStoreCommand()
>> {
>> @Override
>> protected void doRun()
>> {
>> // apply changes to project in here
>> }
>> }.run();
>>
>> // more handler code...
>>
>>
>> Everything was fine then.
>> But since the "EMFStoreCommand" was marked as depricated I was trying
>> to find a solution for the problem.
>> Instead I also tried wrapping the project-modifying code in a Callable
>> like this but it didn't help:
>>
>>
>> // handler code...
>>
>> Callable<Void> call = new Callable<Void>()
>> {
>> @Override
>> public Void call() throws Exception
>> {
>> // apply changes to project in here
>> return null;
>> }
>> };
>>
>> RunESCommand.run(call);
>>
>> // more handler code...
>>
>
>
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| Re: [EMF Client Platform] Modifying content of ECPProject in non-UI thread [message #1159308 is a reply to message #1153205] |
Mon, 28 October 2013 12:42 |
Edgar Mueller
Messages: 89
Registered: March 2011 |
Member |
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Hi Steffen,
unfortunately, I don't think we can fix this problem in a reasonable
way, because it can't be fixed conceptually.
The reason for this is, that EMF expects only one thread at a time to
access the model instance [1].
Apparently, this is not the case, because the UI thread tries to refresh
the viewer that displays the model while the model is being modified.
We'll provide a fix for this, which will block the UI thread in order to
avoid the ConcurrentModificationExcpetion, but, of course, this won't be
of much use to you.
Possible solutions to your problem would be to either use EMF
transaction or use CDO as a backend (for which ECP has a provider).
In case of EMF transaction, you would need to wrap all calls, that
access the model, in commands. See [2] for more info.
For CDO, please see [3].
Hope this helps.
Cheers,
Edgar
[1] http://wiki.eclipse.org/EMF/FAQ#Is_EMF_thread-safe.3F
[2] http://www.eclipse.org/modeling/emf/?project=transaction
[3] http://www.eclipse.org/cdo/
Am 24.10.2013 14:52, schrieb Eugen Neufeld:
> Hi Steffen,
> the issue is more cumbersome then we thought.
>
> We are about to fix this.
> But we won't create a hotfix release for this.
> The fix will be in the 1.1.0 release which will be on Tuesday next week.
>
> Cheers,
> Eugen
>
>
--
Edgar Mueller
Get Professional Eclipse Support: http://eclipsesource.com/munich
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| Re: [EMF Client Platform] Modifying content of ECPProject in non-UI thread [message #1219456 is a reply to message #1219351] |
Tue, 03 December 2013 22:58 |
Steffen Lehnert
Messages: 22
Registered: October 2013 |
Junior Member |
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Hi Edgar,
thank you for your message and help.
Unfortunately, even with the modified code (I just copied your example) I'm still running into ConcurrentModificationExceptions.
Based on the stacktrace, the EMFStoreProvider is already used (see the attachment).
Also, I've configured my client based on this tutorial if that's of any help to you:
Getting started with EMFStore
Cheers,
Steffen
Edgar Mueller wrote on Tue, 03 December 2013 08:42Hi Steffen,
sorry for the delay. Regarding your question: it depends on the backend
provider you are using. The easiest way, at least from my perspective,
would be to use the EMFStore backend provider together with the
transactional support provided by EMFStore.
The transactional support feature is available on the EMFStore update
site (http://download.eclipse.org/emf-store/releases/) under the
'EMFStore Additional Features' section.
Additionally, you will need to adapt your code within your run method:
// this will return a TransactionalEditingDomain
final EditingDomain editingDomain = project[0].getEditingDomain();
....
for (int i = 0; i < 1000; i++) {
final Player createPlayer = createPlayer("Player " + i);
editingDomain.getCommandStack().execute(
// create custom change command
new ChangeCommand(createPlayer) {
@Override
protected void doExecute() {
project[0].getContents().add(createPlayer);
}
});
}
So you need to fetch the CommandStack of the TransactionalEditingDomain
and execute a custom ChangeCommand on it, which holds the code that
modifies the ECP project.
Hope this helps.
Cheers
Edgar
Am 01.12.2013 22:37, schrieb Steffen Lehnert:
> Hi Edgar,
>
> the call to "project.getEditingDomain()" returns a
> "AdapterFactoryEditingDomain".
> The provider of the project returned by "project.getProvider()" is
> "ECPProvider".
>
> How do I get a "TransactionalEditingDomain" for the project based on the
> above information?
>
> Thanks for your help,
> Steffen
--
Edgar Mueller
Get Professional Eclipse Support: http://eclipsesource.com/munich
[Updated on: Tue, 03 December 2013 22:59] Report message to a moderator |
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| Re: [EMF Client Platform] Modifying content of ECPProject in non-UI thread [message #1219510 is a reply to message #1219456] |
Wed, 04 December 2013 10:56 |
Edgar Mueller
Messages: 89
Registered: March 2011 |
Member |
|
|
Hi Steffen,
copying the modified code is not enough, did you also install the
transactional support for EMFStore? If so, can you check whether it is
present in your running config
(org.eclipse.emf.emfstore.client.transaction and
org.eclipse.emf.transaction)?
For the example I gave the use of a transactional EditingDomain is
mandatory. I tried the example myself and it did work for me.
Cheers,
Edgar
> Hi Edgar,
>
> thank you for your message.
> Unfortunately, even with the modified code (I just copied your example) I'm still running into ConcurrentModificationExceptions.
> Based on the stacktrace, the EMFStoreProvider is already used.
> Also, I've configured my client based on this tutorial if that's of any help to you:
> http://eclipsesource.com/blogs/tutorials/getting-started-with-emfstore/#run
>
> Cheers,
> Steffen
>
--
Edgar Mueller
Get Professional Eclipse Support: http://eclipsesource.com/munich
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