null pointer exception in HS running Rect.hack

[cpainterwakefield]

I'm getting a Null Pointer Exception from the Hardware Simulator when testing my Computer.hdl using the ComputerRect.tst.  The traceback is below.

I'm running with the slider set to Fast, no animation, view screen.

No error message is returned from the GUI - it just stops doing anything.  I find that I can continue and complete the tests by clicking on the stop button and then on the run button again.  The program sometimes stops again, this time with a different traceback (see below), but again I can continue by clicking on stop, run.  The program successfully draws the rectangle.

Java particulars:
java version "1.7.0_55"
OpenJDK Runtime Environment (IcedTea 2.4.7) (7u55-2.4.7-1ubuntu1)
OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)

First traceback:
Exception in thread "Thread-3" java.lang.NullPointerException
        at javax.swing.BufferStrategyPaintManager.prepare(BufferStrategyPaintManager.java:526)
        at javax.swing.BufferStrategyPaintManager.copyArea(BufferStrategyPaintManager.java:322)
        at javax.swing.RepaintManager.copyArea(RepaintManager.java:1264)
        at javax.swing.JViewport.blitDoubleBuffered(JViewport.java:1596)
        at javax.swing.JViewport.windowBlitPaint(JViewport.java:1559)
        at javax.swing.JViewport.setViewPosition(JViewport.java:1102)
        at javax.swing.JViewport.scrollRectToVisible(JViewport.java:439)
        at javax.swing.JComponent.scrollRectToVisible(JComponent.java:3098)
        at HackGUI.Utilities.tableCenterScroll(Unknown Source)
        at HackGUI.PointedMemoryComponent.setPointer(Unknown Source)
        at builtInChips.RAM.reCompute(Unknown Source)
        at Hack.Gates.Gate.doEval(Unknown Source)
        at Hack.Gates.Gate.eval(Unknown Source)
        at Hack.Gates.CompositeGate.reCompute(Unknown Source)
        at Hack.Gates.Gate.doEval(Unknown Source)
        at Hack.Gates.Gate.eval(Unknown Source)
        at Hack.Gates.CompositeGate.reCompute(Unknown Source)
        at Hack.Gates.Gate.doEval(Unknown Source)
        at Hack.Gates.Gate.tock(Unknown Source)
        at Hack.HardwareSimulator.HardwareSimulator.performTock(Unknown Source)
        at Hack.HardwareSimulator.HardwareSimulator.doCommand(Unknown Source)
        at Hack.Controller.HackController.miniStep(Unknown Source)
        at Hack.Controller.HackController.singleStep(Unknown Source)
        at Hack.Controller.HackController.access$000(Unknown Source)
        at Hack.Controller.HackController$FastForwardTask.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:744)

Second traceback:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.BufferStrategyPaintManager.flushAccumulatedRegion(BufferStrategyPaintManager.java:416)
        at javax.swing.BufferStrategyPaintManager.endPaint(BufferStrategyPaintManager.java:380)
        at javax.swing.RepaintManager.endPaint(RepaintManager.java:1313)
        at javax.swing.JComponent._paintImmediately(JComponent.java:5164)
        at javax.swing.JComponent.paintImmediately(JComponent.java:4969)
        at javax.swing.RepaintManager$3.run(RepaintManager.java:808)
        at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
        at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:769)
        at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:718)
        at javax.swing.RepaintManager.access$1100(RepaintManager.java:62)
        at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1677)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
        at java.awt.EventQueue.access$200(EventQueue.java:103)
        at java.awt.EventQueue$3.run(EventQueue.java:694)
        at java.awt.EventQueue$3.run(EventQueue.java:692)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Exception in thread "Thread-4" java.lang.NullPointerException
        at javax.swing.BufferStrategyPaintManager.prepare(BufferStrategyPaintManager.java:526)
        at javax.swing.BufferStrategyPaintManager.copyArea(BufferStrategyPaintManager.java:322)
        at javax.swing.RepaintManager.copyArea(RepaintManager.java:1264)
        at javax.swing.JViewport.blitDoubleBuffered(JViewport.java:1596)
        at javax.swing.JViewport.windowBlitPaint(JViewport.java:1559)
        at javax.swing.JViewport.setViewPosition(JViewport.java:1102)
        at javax.swing.JViewport.scrollRectToVisible(JViewport.java:439)
        at javax.swing.JComponent.scrollRectToVisible(JComponent.java:3098)
        at HackGUI.Utilities.tableCenterScroll(Unknown Source)
        at HackGUI.PointedMemoryComponent.setPointer(Unknown Source)
        at builtInChips.ROM32K.reCompute(Unknown Source)
        at Hack.Gates.Gate.doEval(Unknown Source)
        at Hack.Gates.Gate.eval(Unknown Source)
        at Hack.Gates.CompositeGate.reCompute(Unknown Source)
        at Hack.Gates.Gate.doEval(Unknown Source)
        at Hack.Gates.Gate.tock(Unknown Source)
        at Hack.HardwareSimulator.HardwareSimulator.performTock(Unknown Source)
        at Hack.HardwareSimulator.HardwareSimulator.doCommand(Unknown Source)
        at Hack.Controller.HackController.miniStep(Unknown Source)
        at Hack.Controller.HackController.singleStep(Unknown Source)
        at Hack.Controller.HackController.access$000(Unknown Source)
        at Hack.Controller.HackController$FastForwardTask.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:744)

 

[cadet1620]

Looks like you are running Linux.

I'm not a Java programmer, so I can only report my experiences and observations...

I've never had any problems running the n2t tools on 32-bit Ubuntu Linux, but I haven't worked it very hard. I doubt I've tried any of the Computer tests.

The crash traces all look like drawing problems, two of them with scrolling.

Under Windows XP I've seen strange problems if the HDL contains more parts with UI than are expected.  For instance, if there are multiple RAM16Ks in Memory.hdl. (I was experimenting with caching...) The part windows end up in strange places.

There appear to be issues related to threads running on multiple processor cores. I've seen things drawn in the wrong place, which symptomatic of bad/stale pointers, which could easily result in crashes like you are getting. I was able to eliminate this problem by limiting Java to a single core. (IIRC, this was when I was playing with multiple RAMs.)

If you want to, zip up your entire projects/05 directory and send it to me. I'll let you know if I see anything and if I can reproduce the problem on 32-bit Linux or 64-bit Win7. My Dell PC hates 64-bit Ubuntu for some reason. 8-(

--Mark

[cpainterwakefield]

Mark,

I am faculty, and a Java programmer.  If you send me the source for the hardware simulator, I can debug on my end.

-Christopher
[e-mail]

[ybakos]

Christopher (hi!) -- does the Simulator only puke when you use your Computer.hdl? Do other chip tests work ok? Are you using any custom chips in your implementation within the particular project directory?

[cadet1620]

The only source I have access to is the one on the n2t web site.
http://www.nand2tetris.org/software/nand2tetris-open-source-2.5.7.zip

--Mark

[cpainterwakefield]

Hi Yong :)

yes, yes, no.

-Christopher

[ybakos]

Perhaps email me your Computer.hdl as a file attachment so I can take a look, just to be sure.

[cpainterwakefield]

Yong, just Computer.hdl, or do you also want Memory.hdl and CPU.hdl?

[ybakos]

Tell you what, send me a zip of the entire directory, so I can try to replicate the issue.

[cpainterwakefield]

sure.  Is your Mines address active, or do you have another email I should use?

Thanks,
Christopher

On 07/31/2014 01:13 PM, ybakos [via Nand2Tetris Questions and Answers Forum] wrote:

Tell you what, send me a zip of the entire directory, so I can try to replicate the issue.

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[ybakos]

Well, this won't help much but your 05 stuff works without issues for me.

My env:
OSX 10.10
java version "1.7.0_40"
Java(TM) SE Runtime Environment (build 1.7.0_40-b43)
Java HotSpot(TM) 64-Bit Server VM (build 24.0-b56, mixed mode)