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javaeclipsepluginsclassloader

Classloading conflict with two eclipse plugins


Following situation:

At work we have an own plugin that extends some JDT features and builds some helper functions for our own framework. So far so good.

The plugin includes following class:

public class MoxLogFactory extends org.apache.commons.logging.LogFactory {   
    ...
}

(I left out the concrete implementation because it's really comprehensive)

Now I added the WindowBuilder-Plugin to my eclipse installation. I can create new projects and classes with the wizards included. But the main feature - the editor himself - isn't working. It comes out, that the WindowBuilder tries to load the class "MoxLogFactory" from our plugin! I attached the stacktrace which comes up if I open the editor:

java.lang.ClassNotFoundException: org.dreamox.moxanos.log.MoxLogFactory
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.apache.commons.logging.LogFactory.createFactory(LogFactory.java:1261)
at org.apache.commons.logging.LogFactory$2.run(LogFactory.java:1065)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.commons.logging.LogFactory.newFactory(LogFactory.java:1062)
at org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:497)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:704)
at org.apache.commons.digester.Digester.<init>(Digester.java:340)
at org.eclipse.wb.internal.core.model.description.helpers.ComponentDescriptionHelper.getDescription0(ComponentDescriptionHelper.java:375)
at org.eclipse.wb.internal.core.model.description.helpers.ComponentDescriptionHelper.getDescription0(ComponentDescriptionHelper.java:289)
at org.eclipse.wb.internal.core.model.description.helpers.ComponentDescriptionHelper.getDescription(ComponentDescriptionHelper.java:258)
at org.eclipse.wb.internal.core.model.JavaInfoUtils.createJavaInfo(JavaInfoUtils.java:386)
at org.eclipse.wb.internal.rcp.parser.ParseFactory.getRootContext(ParseFactory.java:184)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.prepareParseContext(JavaInfoParser.java:1185)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.parse(JavaInfoParser.java:244)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.access$9(JavaInfoParser.java:240)
at org.eclipse.wb.internal.core.parser.JavaInfoParser$1.runObject(JavaInfoParser.java:153)
at org.eclipse.wb.internal.core.parser.JavaInfoParser$1.runObject(JavaInfoParser.java:1)
at org.eclipse.wb.internal.core.utils.execution.ExecutionUtils.runDesignTime(ExecutionUtils.java:153)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.parse(JavaInfoParser.java:151)
at org.eclipse.wb.internal.core.editor.DesignPage.internal_refreshGEF(DesignPage.java:522)
at org.eclipse.wb.internal.core.editor.DesignPage.access$9(DesignPage.java:510)
at org.eclipse.wb.internal.core.editor.DesignPage$8$1.run(DesignPage.java:437)
at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:180)
at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:150)
at org.eclipse.swt.widgets.Display.syncExec(Display.java:4683)
at org.eclipse.wb.internal.core.editor.DesignPage$8.run(DesignPage.java:434)
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:464)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:372)
at org.eclipse.jface.dialogs.ProgressMonitorDialog.run(ProgressMonitorDialog.java:507)
at org.eclipse.wb.internal.core.editor.DesignPage.internal_refreshGEF_withProgress(DesignPage.java:453)
at org.eclipse.wb.internal.core.editor.DesignPage.internal_refreshGEF(DesignPage.java:403)
at org.eclipse.wb.internal.core.editor.UndoManager.refreshDesignerEditor(UndoManager.java:381)
at org.eclipse.wb.internal.core.editor.UndoManager.activate(UndoManager.java:90)
at org.eclipse.wb.internal.core.editor.DesignPage.handleActiveState_True(DesignPage.java:251)
at org.eclipse.wb.internal.core.editor.DesignPage.handleActiveState(DesignPage.java:229)
at org.eclipse.wb.internal.core.editor.multi.DefaultMultiMode.showPage(DefaultMultiMode.java:125)
at org.eclipse.wb.internal.core.editor.multi.DefaultMultiMode$1.widgetSelected(DefaultMultiMode.java:63)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:240)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1062)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:774)
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:2746)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1433)
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:257)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:999)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:893)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:85)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:579)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:534)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:352)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:624)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:579)
at org.eclipse.equinox.launcher.Main.run(Main.java:1433)
at org.eclipse.equinox.launcher.Main.main(Main.java:1409)

Our plugin doesn't export anything, so why is the WindowBuilder trying to load a class from it? Where do it gets the information to load this class? If I uninstall our plugin the WindowBuilder works fine, but I need both plugins to work efficiently.

I found, that in MoxLogFactory in one static method there is a line

System.setProperty("org.apache.commons.logging.LogFactory","org.dreamox.moxanos.log.MoxLogFactory");

I thought every plugin runs in a sandbox and so this isn't really a problem, but when I see the stacktrace, it seems, that this system property is "global in eclipse". The MoxLogFactory class is also used in our application server framework so this code is needed - the plugin uses the framework itself to work.

I don't know how to solve this problem and would appreciate any hint or idea.


Solution

  • Here are some options:

    • Remove that static initialization of the JVM level system property and replace it by a command line option only when needed

    • In your static initializer, test Eclipse execution context by asking the ClassLoader for org.eclipse.equinox.launcher.Main class for instance, and if so, do not set the logfactory property