com.sun.jdi.VMDisconnectedException: connection is closed
        at com.sun.tools.jdi.TargetVM.send(TargetVM.java:274)
        at com.sun.tools.jdi.VirtualMachineImpl.sendToTarget(VirtualMachineImpl.java:1011)
        at com.sun.tools.jdi.PacketStream.send(PacketStream.java:41)
        at com.sun.tools.jdi.JDWP$ThreadReference$FrameCount.enqueueCommand(JDWP.java:5300)
        at com.sun.tools.jdi.JDWP$ThreadReference$FrameCount.process(JDWP.java:5286)
        at com.sun.tools.jdi.ThreadReferenceImpl.frameCount(ThreadReferenceImpl.java:254)
        at org.netbeans.modules.debugger.jpda.models.JPDAThreadImpl.getStackDepth(JPDAThreadImpl.java:512)
        at org.netbeans.modules.debugger.jpda.ui.models.DebuggingNodeModel.getDisplayName(DebuggingNodeModel.java:212)
        at org.netbeans.modules.debugger.jpda.ui.models.DebuggingNodeModel.getDisplayName(DebuggingNodeModel.java:174)
        at org.netbeans.spi.viewmodel.Models$DelegatingNodeModel.getDisplayName(Models.java:1869)
        at org.netbeans.modules.debugger.jpda.ui.models.DebuggingMonitorModel.getDisplayName(DebuggingMonitorModel.java:380)
        at org.netbeans.spi.viewmodel.Models$CompoundNodeModel.getDisplayName(Models.java:813)
        at org.netbeans.spi.viewmodel.Models$CompoundModel.getDisplayName(Models.java:3023)
        at org.netbeans.modules.viewmodel.TreeModelNode.refreshNode(TreeModelNode.java:416)
        at org.netbeans.modules.viewmodel.TreeModelNode.<init>(TreeModelNode.java:135)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.createNodes(TreeModelNode.java:919)
        at org.openide.nodes.Children$Keys$KE.nodes(Children.java:1517)
        at org.openide.nodes.ChildrenArray.nodesFor(ChildrenArray.java:168)
        at org.openide.nodes.EntrySupport$Default$Info.nodes(EntrySupport.java:935)
        at org.openide.nodes.EntrySupport$Default.justComputeNodes(EntrySupport.java:234)
        at org.openide.nodes.ChildrenArray.nodes(ChildrenArray.java:101)
        at org.openide.nodes.EntrySupport$Default.setEntries(EntrySupport.java:302)
        at org.openide.nodes.Children$Keys$2.run(Children.java:1411)
        at org.openide.util.Mutex.postRequest(Mutex.java:1262)
        at org.openide.util.Mutex.postWriteRequest(Mutex.java:582)
        at org.openide.nodes.Children$Keys.applyKeys(Children.java:1420)
        at org.openide.nodes.Children$Keys.setKeys(Children.java:1401)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.applyChildren(TreeModelNode.java:848)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.refreshLazyChildren(TreeModelNode.java:822)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.refreshChildren(TreeModelNode.java:740)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.addNotify(TreeModelNode.java:729)
        at org.openide.nodes.Children.callAddNotify(Children.java:525)
        at org.openide.nodes.EntrySupport$Default.getArray(EntrySupport.java:736)
        at org.openide.nodes.EntrySupport$Default.setEntries(EntrySupport.java:298)
        at org.openide.nodes.Children$Keys$2.run(Children.java:1411)
        at org.openide.util.Mutex.postRequest(Mutex.java:1262)
        at org.openide.util.Mutex.postWriteRequest(Mutex.java:582)
        at org.openide.nodes.Children$Keys.applyKeys(Children.java:1420)
        at org.openide.nodes.Children$Keys.setKeys(Children.java:1364)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.removeNotify(TreeModelNode.java:734)
        at org.openide.nodes.EntrySupport$Default.finalizedChildrenArray(EntrySupport.java:890)
        at org.openide.nodes.ChildrenArray.finalize(ChildrenArray.java:84)
        at java.lang.ref.Finalizer.invokeFinalizeMethod(Finalizer.java:0)
        at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:83)
        at java.lang.ref.Finalizer.access$100(Finalizer.java:14)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:160)