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Although I do not know how to reproduce this problem, I get the following exception(s) from time to time. Eclipse 3.1.1 + WTP, IBM JDK j9n142-20050929, WinXP SP2. !ENTRY org.eclipse.core.resources 4 2 2005-10-31 11:33:07.837 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources". !STACK 0 java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[Worker-66,5,main] at java.util.HashMap.onEntry(HashMap.java:211) at java.util.HashMap.transfer(HashMap.java:554) at java.util.HashMap.resize(HashMap.java:541) at java.util.HashMap.addEntry(HashMap.java:901) at java.util.HashMap.put(HashMap.java:474) at java.util.HashSet.add(HashSet.java:206) at org.eclipse.jdt.internal.core.JavaModel.getTarget(JavaModel.java:372) at org.eclipse.jdt.internal.core.ClasspathEntry.validateClasspathEntry(ClasspathEntry.java:1591) at org.eclipse.jdt.internal.core.JavaProject.getResolvedClasspath(JavaProject.java:2059) at org.eclipse.jdt.internal.core.JavaProject.getResolvedClasspath(JavaProject.java:1954) at org.eclipse.jdt.internal.core.DeltaProcessor.updateClasspathMarkers(DeltaProcessor.java:2073) at org.eclipse.jdt.internal.core.DeltaProcessor.updateClasspathMarkers(DeltaProcessor.java:2103) at org.eclipse.jdt.internal.core.DeltaProcessor.updateClasspathMarkers(DeltaProcessor.java:2119) at org.eclipse.jdt.internal.core.DeltaProcessor.resourceChanged(DeltaProcessor.java:1823) at org.eclipse.jdt.internal.core.DeltaProcessingState.resourceChanged(DeltaProcessingState.java:432) at org.eclipse.core.internal.events.NotificationManager$2.run(NotificationManager.java:276) at org.eclipse.core.internal.runtime.InternalPlatform.run(InternalPlatform.java:1044) at org.eclipse.core.runtime.Platform.run(Platform.java:783) at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:270) at org.eclipse.core.internal.events.NotificationManager.broadcastChanges(NotificationManager.java:144) at org.eclipse.core.internal.resources.Workspace.broadcastBuildEvent(Workspace.java:185) at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:137) at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:200) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:76) !ENTRY org.eclipse.ui 4 4 2005-10-31 11:33:07.868 !MESSAGE Unhandled event loop exception !ENTRY org.eclipse.ui 4 0 2005-10-31 11:33:07.868 !MESSAGE Failed to execute runnable (java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[main,6,main]) Unhandled event loop exception Reason: !STACK 0 org.eclipse.swt.SWTException: Failed to execute runnable (java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[main,6,main]) at org.eclipse.swt.SWT.error(SWT.java:2942) at org.eclipse.swt.SWT.error(SWT.java:2865) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:126) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3057) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2716) at org.eclipse.ui.internal.dialogs.EventLoopProgressMonitor.runEventLoop(EventLoopProgressMonitor.java:123) at org.eclipse.ui.internal.dialogs.EventLoopProgressMonitor.done(EventLoopProgressMonitor.java:82) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1731) at org.eclipse.ui.actions.WorkspaceModifyOperation.run(WorkspaceModifyOperation.java:110) at org.eclipse.ui.internal.editors.text.WorkspaceOperationRunner.run(WorkspaceOperationRunner.java:73) at org.eclipse.ui.internal.editors.text.WorkspaceOperationRunner.run(WorkspaceOperationRunner.java:63) at org.eclipse.ui.editors.text.TextFileDocumentProvider.executeOperation(TextFileDocumentProvider.java:441) at org.eclipse.ui.editors.text.TextFileDocumentProvider.saveDocument(TextFileDocumentProvider.java:700) at org.eclipse.ui.texteditor.AbstractTextEditor.performSave(AbstractTextEditor.java:3736) at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor.performSave(CompilationUnitEditor.java:1405) at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor.doSave(CompilationUnitEditor.java:1458) at org.eclipse.ui.internal.SaveableHelper$1.run(SaveableHelper.java:95) at org.eclipse.ui.internal.SaveableHelper$2.run(SaveableHelper.java:116) at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:346) at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:291) at org.eclipse.jface.window.ApplicationWindow$1.run(ApplicationWindow.java:624) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:69) at org.eclipse.jface.window.ApplicationWindow.run(ApplicationWindow.java:621) at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2134) at org.eclipse.ui.internal.SaveableHelper.runProgressMonitorOperation(SaveableHelper.java:122) at org.eclipse.ui.internal.SaveableHelper.savePart(SaveableHelper.java:100) at org.eclipse.ui.internal.EditorManager.savePart(EditorManager.java:1154) at org.eclipse.ui.internal.WorkbenchPage.savePart(WorkbenchPage.java:2714) at org.eclipse.ui.internal.WorkbenchPage.saveEditor(WorkbenchPage.java:2727) at org.eclipse.ui.internal.SaveAction.run(SaveAction.java:69) at org.eclipse.jface.action.Action.runWithEvent(Action.java:996) at org.eclipse.jface.commands.ActionHandler.execute(ActionHandler.java:117) at org.eclipse.core.commands.Command.execute(Command.java:311) at org.eclipse.core.commands.ParameterizedCommand.execute(ParameterizedCommand.java:396) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.executeCommand(WorkbenchKeyboard.java:459) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.press(WorkbenchKeyboard.java:781) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.processKeyEvent(WorkbenchKeyboard.java:828) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.filterKeySequenceBindings(WorkbenchKeyboard.java:550) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.access$3(WorkbenchKeyboard.java:493) at org.eclipse.ui.internal.keys.WorkbenchKeyboard$KeyDownFilter.handleEvent(WorkbenchKeyboard.java:117) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66) at org.eclipse.swt.widgets.Display.filterEvent(Display.java:917) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:842) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:867) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:852) at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:880) at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:876) at org.eclipse.swt.widgets.Widget.wmChar(Widget.java:1190) at org.eclipse.swt.widgets.Control.WM_CHAR(Control.java:3135) at org.eclipse.swt.widgets.Control.windowProc(Control.java:3038) at org.eclipse.swt.widgets.Display.windowProc(Display.java:3706) at org.eclipse.swt.internal.win32.OS.DispatchMessageW(Native Method) at org.eclipse.swt.internal.win32.OS.DispatchMessage(OS.java:1656) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2711) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:1699) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1663) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:367) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:143) at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java:103) at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:226) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:376) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:163) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:85) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:58) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:60) at java.lang.reflect.Method.invoke(Method.java:391) at org.eclipse.core.launcher.Main.invokeFramework(Main.java:334) at org.eclipse.core.launcher.Main.basicRun(Main.java:278) at org.eclipse.core.launcher.Main.run(Main.java:973) at org.eclipse.core.launcher.Main.main(Main.java:948) Caused by: java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[main,6,main] at java.util.HashMap.onExit(HashMap.java:223) at java.util.HashMap.transfer(HashMap.java:558) at java.util.HashMap.resize(HashMap.java:541) at java.util.HashMap.addEntry(HashMap.java:901) at java.util.HashMap.put(HashMap.java:474) at java.util.HashSet.add(HashSet.java:206) at org.eclipse.jdt.internal.core.JavaModel.getTarget(JavaModel.java:372) at org.eclipse.jdt.internal.core.JavaProject.computePackageFragmentRoots(JavaProject.java:522) at org.eclipse.jdt.internal.core.JavaProject.computePackageFragmentRoots(JavaProject.java:625) at org.eclipse.jdt.internal.core.JavaProject.computePackageFragmentRoots(JavaProject.java:586) at org.eclipse.jdt.internal.core.JavaProject.findPackageFragmentRoots(JavaProject.java:1097) at org.eclipse.jdt.internal.ui.packageview.ClassPathContainer.contains(ClassPathContainer.java:190) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerContentProvider.internalGetParent(PackageExplorerContentProvider.java:231) at org.eclipse.jdt.ui.StandardJavaElementContentProvider.getParent(StandardJavaElementContentProvider.java:231) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerContentProvider.getParent(PackageExplorerContentProvider.java:215) at org.eclipse.jdt.internal.ui.packageview.WorkingSetAwareContentProvider.getModelPath(WorkingSetAwareContentProvider.java:142) at org.eclipse.jdt.internal.ui.packageview.WorkingSetAwareContentProvider.getTreePaths(WorkingSetAwareContentProvider.java:126) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerPart$PackageExplorerProblemTreeViewer.setSelectionToWidget(PackageExplorerPart.java:645) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1208) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerPart$PackageExplorerProblemTreeViewer.preservingSelection(PackageExplorerPart.java:624) at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1289) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerContentProvider$3.run(PackageExplorerContentProvider.java:615) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerContentProvider$7.run(PackageExplorerContentProvider.java:659) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:123) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3057) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2716) at org.eclipse.ui.internal.dialogs.EventLoopProgressMonitor.runEventLoop(EventLoopProgressMonitor.java:123) at org.eclipse.ui.internal.dialogs.EventLoopProgressMonitor.done(EventLoopProgressMonitor.java:82) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1731) at org.eclipse.ui.actions.WorkspaceModifyOperation.run(WorkspaceModifyOperation.java:110) at org.eclipse.ui.internal.editors.text.WorkspaceOperationRunner.run(WorkspaceOperationRunner.java:73) at org.eclipse.ui.internal.editors.text.WorkspaceOperationRunner.run(WorkspaceOperationRunner.java:63) at org.eclipse.ui.editors.text.TextFileDocumentProvider.executeOperation(TextFileDocumentProvider.java:441) at org.eclipse.ui.editors.text.TextFileDocumentProvider.saveDocument(TextFileDocumentProvider.java:700) at org.eclipse.ui.texteditor.AbstractTextEditor.performSave(AbstractTextEditor.java:3736) at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor.performSave(CompilationUnitEditor.java:1405) at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor.doSave(CompilationUnitEditor.java:1458) at org.eclipse.ui.internal.SaveableHelper$1.run(SaveableHelper.java:95) at org.eclipse.ui.internal.SaveableHelper$2.run(SaveableHelper.java:116) at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:346) at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:291) at org.eclipse.jface.window.ApplicationWindow$1.run(ApplicationWindow.java:624) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:69) at org.eclipse.jface.window.ApplicationWindow.run(ApplicationWindow.java:621) at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2134) at org.eclipse.ui.internal.SaveableHelper.runProgressMonitorOperation(SaveableHelper.java:122) at org.eclipse.ui.internal.SaveableHelper.savePart(SaveableHelper.java:100) at org.eclipse.ui.internal.EditorManager.savePart(EditorManager.java:1154) at org.eclipse.ui.internal.WorkbenchPage.savePart(WorkbenchPage.java:2714) at org.eclipse.ui.internal.WorkbenchPage.saveEditor(WorkbenchPage.java:2727) at org.eclipse.ui.internal.SaveAction.run(SaveAction.java:69) at org.eclipse.jface.action.Action.runWithEvent(Action.java:996) at org.eclipse.jface.commands.ActionHandler.execute(ActionHandler.java:117) at org.eclipse.core.commands.Command.execute(Command.java:311) at org.eclipse.core.commands.ParameterizedCommand.execute(ParameterizedCommand.java:396) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.executeCommand(WorkbenchKeyboard.java:459) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.press(WorkbenchKeyboard.java:781) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.processKeyEvent(WorkbenchKeyboard.java:828) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.filterKeySequenceBindings(WorkbenchKeyboard.java:550) at org.eclipse.ui.internal.keys.WorkbenchKeyboard.access$3(WorkbenchKeyboard.java:493) at org.eclipse.ui.internal.keys.WorkbenchKeyboard$KeyDownFilter.handleEvent(WorkbenchKeyboard.java:117) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66) at org.eclipse.swt.widgets.Display.filterEvent(Display.java:917) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:842) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:867) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:852) at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:880) at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:876) at org.eclipse.swt.widgets.Widget.wmChar(Widget.java:1190) at org.eclipse.swt.widgets.Control.WM_CHAR(Control.java:3135) at org.eclipse.swt.widgets.Control.windowProc(Control.java:3038) at org.eclipse.swt.widgets.Display.windowProc(Display.java:3706) at org.eclipse.swt.internal.win32.OS.DispatchMessageW(Native Method) at org.eclipse.swt.internal.win32.OS.DispatchMessage(OS.java:1656) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2711) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:1699) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1663) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:367) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:143) at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java:103) at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:226) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:376) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:163) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:85) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:58) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:60) at java.lang.reflect.Method.invoke(Method.java:391) at org.eclipse.core.launcher.Main.invokeFramework(Main.java:334) at org.eclipse.core.launcher.Main.basicRun(Main.java:278) at org.eclipse.core.launcher.Main.run(Main.java:973) at org.eclipse.core.launcher.Main.main(Main.java:948) Failed to execute runnable (java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[main,6,main])
*** Bug 118444 has been marked as a duplicate of this bug. ***
Changed code to ensure that access to JavaModel#existingExternalFiles and JavaCModel#existingExternalConfirmedFiles is synchronized.
*** Bug 119081 has been marked as a duplicate of this bug. ***
I just happened to look at this. Forgive me if I am sticking my nose out here, but the meaning of the the exception has *nothing* to do with it being synchronized or not. (Although it could under some circumstances) Here is an example of the error. HashMap<String,String> m = new HashMap<String,String>() ; m.put("foo","bar") ; m.put("fu","bar") ; for(String s: m.values()) { m.clear() ; } You modified the list while you were iterating over it. That is the error. Cheers, Eric
We're never removing anything from this set. We're only adding or getting. The problem could only occurred if 2 threads were adding at the same time. Synchronizing the access to this set solved the concurrency issue.
Verified for 3.2 M4 using build I20051213-0010
*** Bug 190563 has been marked as a duplicate of this bug. ***
Can a fix be provided for eclipse 3.0.2?
(In reply to comment #8) > Can a fix be provided for eclipse 3.0.2? > This fix has already been backported in the R3_0_maintenance branch as bug 162517.
