Comment 1 Gunnar Wagenknecht 2019-07-04 03:39:01 EDT

eclipse.buildId=4.12.0.I20190605-1800
java.version=11.0.1
java.vendor=Azul Systems, Inc.
BootLoader constants: OS=macosx, ARCH=x86_64, WS=cocoa, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.committers.product -keyring ...
Command-line arguments:  -os macosx -ws cocoa -arch x86_64 -product org.eclipse.epp.package.committers.product -keyring ...

Comment 2 Per Mildner 2019-11-10 10:33:17 EST

Similar backtrace (from OverviewRuler):


Eclipse IDE for Eclipse Committers

Version: 2019-09 R (4.13.0)
Build id: 20190917-1200

macOS 10.14.6 (18G1012)

java version "11.0.2" 2018-10-16 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.2+7-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.2+7-LTS, mixed mode)


Image.internal_new_GC(GCData) line: 1598	
GC.<init>(Drawable, int) line: 262	
GC.<init>(Drawable) line: 223	
OverviewRuler.doubleBufferPaint(GC) line: 675	
OverviewRuler.lambda$1(PaintEvent) line: 585	
1744871240.paintControl(PaintEvent) line: not available	
TypedListener.handleEvent(Event) line: 234	
EventTable.sendEvent(Event) line: 89	
Display.sendEvent(EventTable, Event) line: 4406	
Canvas(Widget).sendEvent(Event) line: 1512	
Canvas(Widget).sendEvent(int, Event, boolean) line: 1535	
Canvas(Widget).sendEvent(int, Event) line: 1520	
Canvas(Control).drawWidget(long, NSGraphicsContext, NSRect) line: 1278	
Canvas.drawWidget(long, NSGraphicsContext, NSRect) line: 176	
Canvas(Widget).drawRect(long, long, NSRect) line: 776	
Canvas.drawRect(long, long, NSRect) line: 170	
Display.windowProc(long, long, long) line: 6043	
OS.objc_msgSendSuper(objc_super, long, long, long, long, boolean) line: not available [native method]	
Display.applicationNextEventMatchingMask(long, long, long, long, long, long) line: 5284	
Display.applicationProc(long, long, long, long, long, long) line: 5716	
OS.objc_msgSend(long, long, long, long, long, boolean) line: not available [native method]	
NSApplication.nextEventMatchingMask(long, NSDate, NSString, boolean) line: 97	
Display.readAndDispatch() line: 3804	
PartRenderingEngine$5.run() line: 1160	
Realm.runWithDefault(Realm, Runnable) line: 338	
PartRenderingEngine.run(MApplicationElement, IEclipseContext) line: 1049	
E4Workbench.createAndRunUI(MApplicationElement) line: 155	
Workbench.lambda$3(Display, WorkbenchAdvisor, int[]) line: 633	
952172944.run() line: not available	
Realm.runWithDefault(Realm, Runnable) line: 338	
Workbench.createAndRunWorkbench(Display, WorkbenchAdvisor) line: 557	
PlatformUI.createAndRunWorkbench(Display, WorkbenchAdvisor) line: 150	
IDEApplication.start(IApplicationContext) line: 150	
EclipseAppHandle.run(Object) line: 203	
EclipseAppLauncher.runApplication(Object) line: 137	
EclipseAppLauncher.start(Object) line: 107	
EclipseStarter.run(Object) line: 400	
EclipseStarter.run(String[], Runnable) line: 255	
NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]	
NativeMethodAccessorImpl.invoke(Object, Object[]) line: 62	
DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 43	
Method.invoke(Object, Object...) line: 566	
Main.invokeFramework(String[], URL[]) line: 660	
Main.basicRun(String[]) line: 597	
Main.run(String[]) line: 1468	
Main.main(String[]) line: 1441

Comment 3 Karsten Thoms 2019-11-11 19:20:34 EST

This must be a race condition. The lines affected here are:

-------------------------
  if (fBuffer == null)
    fBuffer= new Image(fCanvas.getDisplay(), size.x, size.y);

  GC gc= new GC(fBuffer);
-------------------------

The NPE is raised when fBuffer is null. But is initialised just above. fBuffer will be set to null inn handleDispose. So the dispose event comes right while doubleBufferPaint() is processed.

We need some synchronization here. Would synchronized(this) from before creation of GC until last usage of fBuffer be correct here?

Comment 4 Gunnar Wagenknecht 2019-11-12 01:03:53 EST

(In reply to Karsten Thoms from comment #3)
> We need some synchronization here. Would synchronized(this) from before
> creation of GC until last usage of fBuffer be correct here?

I'd go with a local variable avoiding synchronization.

-------------------------
  Image buffer = fBuffer
  if (buffer == null)
    buffer = fBuffer = new Image(fCanvas.getDisplay(), size.x, size.y);

  GC gc= new GC(buffer);
-------------------------

Of course, some regular checks for "disposed" should be done as well.

Comment 5 Per Mildner 2019-11-12 01:18:43 EST

In my code, line 1597 and 1598 in Image are:
		NSGraphicsContext context = NSGraphicsContext.graphicsContextWithBitmapImageRep(imageRep);
		NSGraphicsContext flippedContext = NSGraphicsContext.graphicsContextWithGraphicsPort(context.graphicsPort(), true);

(my NPE is when context comes back null from graphicsContextWithBitmapImageRep()).

I am using a newer version of Eclipse (and swt?) than the original reporter, so perhaps the code has changed a lot. Please let me know and I can create a new report instead.

Comment 6 Per Mildner 2019-11-12 01:43:06 EST

Downloaded Version: 2019-06 (4.12.0)
Build id: 20190614-1200 (which is the same version as the original report, but Build id is a few days later).

It has the following lines as 1596 and 1597
		NSGraphicsContext context = NSGraphicsContext.graphicsContextWithBitmapImageRep(imageRep);
		NSGraphicsContext flippedContext = NSGraphicsContext.graphicsContextWithGraphicsPort(context.graphicsPort(), true);

So, as far as I can tell both the original reporter (in 4.12, line 1597) and I (in 4.13, line 1598) get the NPE when context comes back null from graphicsContextWithBitmapImageRep().

This does not look like the code "if (fBuffer == null) ..." cited above.

Comment 7 Karsten Thoms 2019-11-12 03:34:46 EST

Per, you are right. I have assumed that this could be provoked when GC gets a null reference. I have provoked this with the debugger, the error trace is different then.
So you are right, the NPE occurs when 
  NSGraphicsContext.graphicsContextWithBitmapImageRep(imageRep)
returns null.

Sorry, I have no clue what could cause this. Anything special you have done? Is this occurring frequently?

Comment 8 Per Mildner 2019-11-12 03:47:59 EST

This is coming frequently. 

This is a MacBook Pro that I move between two locations, one with two external screens, one with a single external screen. This could be relevant but I do not know (i.e. I do not remember) whether the problem happens when I have moved the machine (e.g. with a running Eclipse that wakes up to a new screen configuration).

Comment 9 Karsten Thoms 2019-11-12 03:55:38 EST

I have a similar hardware setup, but am still on macOS 10.14.2. I have not such a problem. I'll check once I have upgraded macOS.

Comment 10 Karsten Thoms 2019-11-13 06:07:02 EST

I have found now this NPE in my own error log. I'll set a breakpoint and observe when it happens again.

java.lang.NullPointerException
	at org.eclipse.swt.graphics.Image.internal_new_GC(Image.java:1598)
	at org.eclipse.swt.graphics.GC.<init>(GC.java:262)
	at org.eclipse.swt.graphics.GC.<init>(GC.java:223)
	at org.eclipse.compare.internal.BufferedCanvas.doubleBufferPaint(BufferedCanvas.java:89)
	at org.eclipse.compare.internal.BufferedCanvas.lambda$0(BufferedCanvas.java:40)
	at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:234)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4406)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1512)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1535)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1520)
	at org.eclipse.swt.widgets.Control.drawWidget(Control.java:1278)
	at org.eclipse.swt.widgets.Canvas.drawWidget(Canvas.java:176)
	at org.eclipse.swt.widgets.Widget.drawRect(Widget.java:776)
	at org.eclipse.swt.widgets.Canvas.drawRect(Canvas.java:170)
	at org.eclipse.swt.widgets.Display.windowProc(Display.java:6043)
	at org.eclipse.swt.internal.cocoa.OS.objc_msgSendSuper(Native Method)
	at org.eclipse.swt.widgets.Display.applicationNextEventMatchingMask(Display.java:5284)
	at org.eclipse.swt.widgets.Display.applicationProc(Display.java:5716)
	at org.eclipse.swt.internal.cocoa.OS.objc_msgSend(Native Method)
	at org.eclipse.swt.internal.cocoa.NSApplication.nextEventMatchingMask(NSApplication.java:97)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3804)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1160)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1049)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:660)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:559)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:154)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:150)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:137)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:107)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:401)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:657)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:594)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1438)

Comment 11 Gunnar Wagenknecht 2020-01-23 15:05:53 EST

Created attachment 281590 [details]
Screenshot of missing annotation rulers

I get this quite frequently in 2019-12. I have to close and re-open the Java Editor when it occurs.

Comment 12 Gunnar Wagenknecht 2020-01-27 07:53:15 EST

So this is a Mac specific issue and probably a change (bug?) in Mac that might cause this.

The context can be null of OSX fails to respond here:

public static NSGraphicsContext graphicsContextWithBitmapImageRep(NSBitmapImageRep bitmapRep) {
	long result = OS.objc_msgSend(OS.class_NSGraphicsContext, OS.sel_graphicsContextWithBitmapImageRep_, bitmapRep != null ? bitmapRep.id : 0);
	return result != 0 ? new NSGraphicsContext(result) : null;
}

Comment 13 Lakshmi P Shanmugam 2020-01-29 00:19:10 EST

*** This bug has been marked as a duplicate of bug 548430 ***