Bug 5113

Summary:	NPE in Java Model Presentation
Product:	[Eclipse Project] JDT	Reporter:	Darin Wright <darin.eclipse>
Component:	Debug	Assignee:	Jared Burns <jared_burns>
Status:	RESOLVED DUPLICATE	QA Contact:
Severity:	normal
Priority:	P1	CC:	jared_burns
Version:	2.0
Target Milestone:	---
Hardware:	PC
OS:	Windows 2000
Whiteboard:

Description Darin Wright

2001-10-19 12:14:54 EDT

Running the test suite, many "unable to execute runnable dialogs" appear.
These are due to an NPE in the JavaModelPresentation:

e= SWTException  (id=48)
	backtrace= Object[10]  (id=54)
	code= 46
	detailMessage= "Failed to execute runnable"
	throwable= NullPointerException  (id=59)
		backtrace= Object[30]  (id=67)
			[0]= int[29]  (id=68)
			[1]= Class 
(org.eclipse.jdt.internal.debug.ui.JDIModelPresentation) (id=69)
			[2]= Class 
(org.eclipse.jdt.internal.debug.ui.JDIModelPresentation) (id=69)
			[3]= Class 
(org.eclipse.jdt.internal.debug.ui.JDIModelPresentation) (id=69)
			[4]= Class 
(org.eclipse.debug.internal.ui.LazyModelPresentation) (id=70)
			[5]= Class 
(org.eclipse.debug.internal.ui.DelegatingModelPresentation) (id=71)
			[6]= Class (org.eclipse.jface.viewers.TreeViewer) 
(id=72)
			[7]= Class 
(org.eclipse.jface.viewers.AbstractTreeViewer) (id=73)
			[8]= Class (org.eclipse.jface.viewers.StructuredViewer) 
(id=74)
			[9]= Class 
(org.eclipse.jface.viewers.AbstractTreeViewer) (id=73)
			[10]= Class 
(org.eclipse.jface.viewers.AbstractTreeViewer) (id=73)
			[11]= Class 
(org.eclipse.jface.viewers.AbstractTreeViewer) (id=73)
			[12]= Class 
(org.eclipse.jface.viewers.AbstractTreeViewer) (id=73)
			[13]= Class 
(org.eclipse.jface.viewers.StructuredViewer$1) (id=75)
			[14]= Class 
(org.eclipse.jface.viewers.StructuredViewer) (id=74)
			[15]= Class 
(org.eclipse.jface.viewers.StructuredViewer) (id=74)
			[16]= Class (org.eclipse.debug.internal.ui.DebugView) 
(id=76)
			[17]= Class 
(org.eclipse.debug.internal.ui.LaunchesViewer) (id=77)
			[18]= Class 
(org.eclipse.debug.internal.ui.DebugContentProvider) (id=78)
			[19]= Class 
(org.eclipse.debug.internal.ui.DebugContentProvider) (id=78)
			[20]= Class 
(org.eclipse.debug.internal.ui.BasicContentProvider$1) (id=79)
			[21]= Class (org.eclipse.swt.widgets.RunnableLock) 
(id=80)
			[22]= Class (org.eclipse.swt.widgets.Synchronizer) 
(id=65)
			[23]= Class (org.eclipse.swt.widgets.Display) (id=66)
			[24]= Class (org.eclipse.swt.widgets.Display) (id=66)
			[25]= Class (org.eclipse.ui.internal.Workbench) (id=13)
			[26]= Class (org.eclipse.ui.internal.Workbench) (id=13)
			[27]= Class 
(org.eclipse.core.internal.boot.InternalBootLoader) (id=44)
			[28]= Class (org.eclipse.core.boot.BootLoader) (id=45)
			[29]= Class (SlimLauncher) (id=46)
		detailMessage= null


JDIStackFrame is returning null in many cases (in this case from
getReceivingTypeName), when the VM disconnects, and the retrieval is
being performed. The methods are not documented to return null, and
should actually just throw a DebugException.

Comment 1 Darin Wright

2001-10-19 15:47:53 EDT

Fixed. I changed the implementation of JDIDebugElement#targetRequestFailed
to always throw an exception. We used to hide VMDisconnectedExceptions
when the VM was terminating. However, there are only a handful of situations
where we want to ignore VMDisconnect's, so those are now coded excplicitly.
Anywhere else, a disconnect is an unexpected exception that should be
propagated to the client.

Running the test suite now produces no "Unable to excecute Runnable" dialogs.
(re-assigning for verification).

Comment 2 Darin Wright

2001-10-19 15:48:06 EDT

Please verify.

Comment 3 Jared Burns

2001-11-08 14:50:15 EST

I believe this the cause of a lot of recent trouble on Linux. We're throwing
VMDisconnected exceptions quite a lot now. It's a timing issue, so the bug
cannot be reproduced with 100% accuracy, however it's not hard to make it
happen.

It might take a few tries to see the problem but:
1. Debug a program to a breakpoint.
2. Resume it.
3. We throw a VMDisconnectedException which propogates to the user.

Comment 4 Darin Wright

2001-11-08 15:57:47 EST

Why is the exception being thrown - are we updating/accessing a debug model 
element after the VM has exited?

Comment 5 Darin Swanson

2001-11-13 10:02:21 EST

The VMDisconnected exception is thrown as we send a "resume" command to the 
VM.  It then happily finishes execution BEFORE we have had a chance in the JDI 
packet receive manager to get the reply packet for the resume command.  
Attempting to get the replay packet is what gets the IOException that is thrown 
as a VMDisconnected.  Jared started looking into better ways of handling these 
cases.

Comment 6 Darin Wright

2001-11-14 09:10:53 EST

Assigning to Jared, as he has been enhancing the disconnection support. Unsure 
if this is still a problem.

Comment 7 Jared Burns

2001-11-14 11:03:24 EST


*** This bug has been marked as a duplicate of 5871 ***