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Created attachment 281289 [details] Video showing the problem. I think this is caused by changes for bug 548309. Its not directly a regression, but with the for-loop added for bug 548309 the concurrent modification becomes visible. https://git.eclipse.org/r/#/c/152786/4/org.eclipse.jface.text/src/org/eclipse/jface/text/TextViewer.java Previously, the code just accessed whatever the underlying array was at index N. Now Java throws the exception. I see this *a lot*, its difficult to edit a breakpoint condition as content assist breaks all the time (and I have to re-open the dialog). java.util.ConcurrentModificationException at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909) at java.util.ArrayList$Itr.next(ArrayList.java:859) at org.eclipse.jface.text.TextViewer.fireInputDocumentAboutToBeChanged(TextViewer.java:2748) at org.eclipse.jface.text.TextViewer.setDocument(TextViewer.java:2796) at org.eclipse.jface.text.source.SourceViewer.setDocument(SourceViewer.java:663) at org.eclipse.jface.text.source.SourceViewer.setDocument(SourceViewer.java:603) at org.eclipse.jface.text.TextViewer.handleDispose(TextViewer.java:1809) at org.eclipse.jface.text.source.SourceViewer.handleDispose(SourceViewer.java:791) at org.eclipse.jface.text.TextViewer.lambda$1(TextViewer.java:1723) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:127) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5741) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1423) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1449) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1432) at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1221) at org.eclipse.swt.custom.StyledText.handleDispose(StyledText.java:5980) at org.eclipse.swt.custom.StyledText.lambda$1(StyledText.java:5792) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5741) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1423) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1449) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1428) at org.eclipse.swt.widgets.Widget.release(Widget.java:1240) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:1502) at org.eclipse.swt.widgets.Canvas.releaseChildren(Canvas.java:279) at org.eclipse.swt.widgets.Decorations.releaseChildren(Decorations.java:486) at org.eclipse.swt.widgets.Shell.releaseChildren(Shell.java:3223) at org.eclipse.swt.widgets.Widget.release(Widget.java:1243) at org.eclipse.swt.widgets.Control.release(Control.java:4578) at org.eclipse.swt.widgets.Widget.dispose(Widget.java:529) at org.eclipse.swt.widgets.Shell.dispose(Shell.java:3146) at org.eclipse.jface.window.Window.close(Window.java:335) at org.eclipse.jface.dialogs.Dialog.close(Dialog.java:988) at org.eclipse.jface.preference.PreferenceDialog.close(PreferenceDialog.java:305) at org.eclipse.ui.internal.dialogs.FilteredPreferenceDialog.close(FilteredPreferenceDialog.java:651) at org.eclipse.jface.preference.PreferenceDialog.cancelPressed(PreferenceDialog.java:272) at org.eclipse.jface.preference.PreferenceDialog.buttonPressed(PreferenceDialog.java:237) at org.eclipse.jface.dialogs.Dialog.lambda$0(Dialog.java:619) at org.eclipse.swt.events.SelectionListener$1.widgetSelected(SelectionListener.java:84) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:252) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5741) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1423) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:5000) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4493) at org.eclipse.jface.window.Window.runEventLoop(Window.java:823) at org.eclipse.jface.window.Window.open(Window.java:799) at org.eclipse.ui.dialogs.PropertyDialogAction.run(PropertyDialogAction.java:153) at org.eclipse.jdt.internal.debug.ui.actions.JavaBreakpointPropertiesRulerAction.run(JavaBreakpointPropertiesRulerAction.java:70) at org.eclipse.jface.action.Action.runWithEvent(Action.java:474) at org.eclipse.ui.texteditor.AbstractRulerActionDelegate.runWithEvent(AbstractRulerActionDelegate.java:112) at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:229) at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:579) at org.eclipse.jface.action.ActionContributionItem.lambda$4(ActionContributionItem.java:413) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5741) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1423) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:5000) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4493) 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) Build is: Eclipse SDK Version: 2020-03 (4.15) Build id: I20191219-1800
Probably the race condition should be fixed, but I think reverting the change from bug 548309 is faster.
https://git.eclipse.org/r/#/c/152786/ should be reverted asap and each change verified that it does not break things.
New Gerrit change created: https://git.eclipse.org/r/154893
Sorry, I did not see your communication while preparing a gerrit..
Looking on the optimization made we see that the old code sometimes iterated over listeners without copying them first, but sometimes with a copy. The simplest fix (after reverting optimization back to original state) would be to iterate over a copy of listener lists. Carsten, please provide first a simple revert of the "for each" optimization for TextViewer. Second, please go over all "for each" optimization commits and check if any of them did similar changes like here (iteration over listeners not copied before) , and also revert them too. Third, create a bug describing the problem with listeners in TextViewer (and other cases if there any).
See also bug 558339 comment 4. Same problem.
It looks like my rights are too limited to use the revert button in gerrit. I thought it just creates a new gerrit with the reversion. That is strange - I have the right to create a gerrit..
New Gerrit change created: https://git.eclipse.org/r/154908
(In reply to Andrey Loskutov from comment #5) > Looking on the optimization made we see that the old code sometimes iterated > over listeners without copying them first, but sometimes with a copy. > > The simplest fix (after reverting optimization back to original state) would > be to iterate over a copy of listener lists. Please allow me to stress the fact that this is no fix, imho. It just hides the problem as java has no chance to detect problems in concurrent processing then. > > Carsten, please provide first a simple revert of the "for each" optimization > for TextViewer. done, see https://git.eclipse.org/r/#/c/154908/ > > Second, please go over all "for each" optimization commits and check if any > of them did similar changes like here (iteration over listeners not copied > before) , and also revert them too. Just checked the one where the TextViewer class was part of. > > Third, create a bug describing the problem with listeners in TextViewer (and > other cases if there any). bug 558557 feel free to modify the description if that is not reflecting your point of view.
On a side note, can also occur when using the Java editor. Closing and opening the editor restores content assist functionality.
Gerrit change https://git.eclipse.org/r/154908 was merged to [master]. Commit: http://git.eclipse.org/c/platform/eclipse.platform.text.git/commit/?id=ba62205c35495a3b7a395c97d5e761ae98892ef9
Verified in I20200106-1805
