Deadlock between DocumentUndoManager and Building

[laeubi]

Today I encountered a deadlock DocumentUndoManager tries to SynchronizableDocument.getModificationStamp

"main" #1 [7493] prio=6 os_prio=0 cpu=454823,61ms elapsed=2588,33s tid=0x00007faedc032b10 nid=7493 waiting for monitor entry  [0x00007faee2dfd000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at org.eclipse.core.internal.filebuffers.SynchronizableDocument.getModificationStamp(SynchronizableDocument.java:151)
	- waiting to lock <0x00000000ab1220d8> (a java.lang.Object)
	at org.eclipse.text.undo.DocumentUndoManager$UndoableTextChange.canUndo(DocumentUndoManager.java:163)
	at org.eclipse.core.commands.operations.DefaultOperationHistory.canUndo(DefaultOperationHistory.java:267)
	at org.eclipse.text.undo.DocumentUndoManager.undoable(DocumentUndoManager.java:836)
	at org.eclipse.jface.text.TextViewerUndoManager.undoable(TextViewerUndoManager.java:348)
	at org.eclipse.jface.text.TextViewer.canDoOperation(TextViewer.java:3892)
	at org.eclipse.jface.text.source.SourceViewer.canDoOperation(SourceViewer.java:836)
	at org.eclipse.compare.internal.MergeSourceViewer$TextOperationAction.isEnabled(MergeSourceViewer.java:139)
	at org.eclipse.compare.internal.MergeSourceViewer$TextOperationAction.update(MergeSourceViewer.java:144)
	at org.eclipse.compare.internal.MergeSourceViewer.updateContentDependantActions(MergeSourceViewer.java:818)
	at org.eclipse.compare.internal.MergeSourceViewer$$Lambda/0x00000001014aa3d0.run(Unknown Source)
	at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40)
	at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:132)
	- locked <0x00000000ded89aa0> (a org.eclipse.swt.widgets.RunnableLock)
	at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:5040)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4520)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1151)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1042)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:639)
	at org.eclipse.ui.internal.Workbench$$Lambda/0x00000001003c4708.run(Unknown Source)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:546)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:152)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:208)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:143)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:109)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:439)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:271)
	at java.lang.invoke.DirectMethodHandle$Holder.invokeStatic([email protected]/DirectMethodHandle$Holder)
	at java.lang.invoke.LambdaForm$MH/0x00000001000c6800.invoke([email protected]/LambdaForm$MH)
	at java.lang.invoke.LambdaForm$MH/0x00000001000c6c00.invokeExact_MT([email protected]/LambdaForm$MH)
	at jdk.internal.reflect.DirectMethodHandleAccessor.invokeImpl([email protected]/DirectMethodHandleAccessor.java:155)
	at jdk.internal.reflect.DirectMethodHandleAccessor.invoke([email protected]/DirectMethodHandleAccessor.java:103)
	at java.lang.reflect.Method.invoke([email protected]/Method.java:580)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:668)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:605)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1481)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1454)

while this is locked by Building thread:

"Worker-51: Building" #1206 [22699] prio=5 os_prio=0 cpu=444,47ms elapsed=619,37s tid=0x00007fad4c029750 nid=22699 waiting on condition  [0x00007fadd68ec000]
   java.lang.Thread.State: TIMED_WAITING (parking)
	at jdk.internal.misc.Unsafe.park([email protected]/Native Method)
	- parking to wait for  <0x00000000deda0d80> (a java.util.concurrent.Semaphore$NonfairSync)
	at java.util.concurrent.locks.LockSupport.parkNanos([email protected]/LockSupport.java:269)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire([email protected]/AbstractQueuedSynchronizer.java:756)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos([email protected]/AbstractQueuedSynchronizer.java:1126)
	at java.util.concurrent.Semaphore.tryAcquire([email protected]/Semaphore.java:415)
	at org.eclipse.ui.internal.PendingSyncExec.acquire(PendingSyncExec.java:39)
	at org.eclipse.ui.internal.PendingSyncExec.waitUntilExecuted(PendingSyncExec.java:88)
	at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:142)
	at org.eclipse.swt.widgets.Display.syncExec(Display.java:5960)
	at org.eclipse.compare.internal.Utilities.firePropertyChange(Utilities.java:179)
	at org.eclipse.compare.internal.Utilities.firePropertyChange(Utilities.java:166)
	at org.eclipse.compare.contentmergeviewer.ContentMergeViewer.fireDirtyState(ContentMergeViewer.java:1185)
	at org.eclipse.compare.contentmergeviewer.ContentMergeViewer.setLeftDirty(ContentMergeViewer.java:1201)
	at org.eclipse.compare.contentmergeviewer.TextMergeViewer.updateDirtyState(TextMergeViewer.java:3279)
	at org.eclipse.compare.contentmergeviewer.TextMergeViewer$ContributorInfo.elementDirtyStateChanged(TextMergeViewer.java:1058)
	at org.eclipse.ui.editors.text.TextFileDocumentProvider$FileBufferListener.dirtyStateChanged(TextFileDocumentProvider.java:305)
	at org.eclipse.core.internal.filebuffers.TextFileBufferManager$3.run(TextFileBufferManager.java:671)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.core.internal.filebuffers.TextFileBufferManager.fireDirtyStateChanged(TextFileBufferManager.java:668)
	at org.eclipse.core.internal.filebuffers.ResourceTextFileBuffer$DocumentListener.documentChanged(ResourceTextFileBuffer.java:76)
	at org.eclipse.jface.text.AbstractDocument.doFireDocumentChanged2(AbstractDocument.java:739)
	at org.eclipse.jface.text.AbstractDocument.doFireDocumentChanged(AbstractDocument.java:708)
	at org.eclipse.jface.text.AbstractDocument.doFireDocumentChanged(AbstractDocument.java:692)
	at org.eclipse.jface.text.AbstractDocument.fireDocumentChanged(AbstractDocument.java:766)
	at org.eclipse.jface.text.AbstractDocument.replace(AbstractDocument.java:1091)
	at org.eclipse.core.internal.filebuffers.SynchronizableDocument.replace(SynchronizableDocument.java:176)
	- locked <0x00000000ab1220d8> (a java.lang.Object)
	at org.eclipse.jface.text.AbstractDocument.replace(AbstractDocument.java:1109)
	at org.eclipse.core.internal.filebuffers.SynchronizableDocument.replace(SynchronizableDocument.java:164)
	- locked <0x00000000ab1220d8> (a java.lang.Object)
	at org.eclipse.text.edits.InsertEdit.performDocumentUpdating(InsertEdit.java:78)
	at org.eclipse.text.edits.TextEdit.traverseDocumentUpdating(TextEdit.java:920)
	at org.eclipse.text.edits.TextEdit.traverseDocumentUpdating(TextEdit.java:913)
	at org.eclipse.text.edits.TextEditProcessor.executeDo(TextEditProcessor.java:196)
	at org.eclipse.text.edits.TextEdit.dispatchPerformEdits(TextEdit.java:742)
	at org.eclipse.text.edits.TextEditProcessor.performEdits(TextEditProcessor.java:158)
	at org.eclipse.text.edits.TextEdit.apply(TextEdit.java:714)
	at org.eclipse.text.edits.TextEdit.apply(TextEdit.java:738)
	at org.eclipse.pde.internal.ui.util.PDEModelUtility.generateModelEdits(PDEModelUtility.java:354)
	at org.eclipse.pde.internal.ui.util.PDEModelUtility.modifyModel(PDEModelUtility.java:291)
	at org.eclipse.pde.ds.internal.annotations.DSAnnotationCompilationParticipant.updateProject(DSAnnotationCompilationParticipant.java:447)
	at org.eclipse.pde.ds.internal.annotations.DSAnnotationCompilationParticipant.buildFinished(DSAnnotationCompilationParticipant.java:401)
	at org.eclipse.jdt.internal.core.builder.JavaBuilder.build(JavaBuilder.java:262)
	at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:1077)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:296)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:352)
	at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:441)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:444)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:555)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:503)
	at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:585)
	at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:207)
	at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:300)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

This results in build thread blocked forever and UI freeze. This seems to happen because I have a compare view open, while PDE is modifying the manifest.

[laeubi]

I also encountered similar deadlocks recently but was not able to capture a stack, also in this case it seems that the CompareView was involved. I'm not sure if that is to blame or if the SynchronizableDocument is acquiring locks in wrong order or maybe the document should not be called from different threads (but why the have it synchronized?)

[iloveeclipse]

This part of the stack is guilty, classic mistake: using syncExec() from a job.
That should be done via asyncExec(), because you never know which locks / rules job acquired, you can't try ro acquire also UI lock:

	at org.eclipse.swt.widgets.Display.syncExec(Display.java:5960)
	at org.eclipse.compare.internal.Utilities.firePropertyChange(Utilities.java:179)
	at org.eclipse.compare.internal.Utilities.firePropertyChange(Utilities.java:166)
	at org.eclipse.compare.contentmergeviewer.ContentMergeViewer.fireDirtyState(ContentMergeViewer.java:1185)
	at org.eclipse.compare.contentmergeviewer.ContentMergeViewer.setLeftDirty(ContentMergeViewer.java:1201)
	at org.eclipse.compare.contentmergeviewer.TextMergeViewer.updateDirtyState(TextMergeViewer.java:3279)
	at org.eclipse.compare.contentmergeviewer.TextMergeViewer$ContributorInfo.elementDirtyStateChanged(TextMergeViewer.java:1058)
	at org.eclipse.ui.editors.text.TextFileDocumentProvider$FileBufferListener.dirtyStateChanged(TextFileDocumentProvider.java:305)

[merks]

The last change around this logic used:

		Display.getDefault().execute(runnable);

but that was reverted back to the current state and that state did an asyncExec:

public void execute(Runnable runnable) {
	Objects.requireNonNull(runnable);
	if (isDisposed()) {
		throw new RejectedExecutionException(new SWTException (SWT.ERROR_WIDGET_DISPOSED, null));
	}
	if (thread == Thread.currentThread()) {
		syncExec(runnable);
	} else {
		asyncExec(runnable);
	}
}

And that change too related to deadlock I guess:

eclipse-platform/eclipse.platform@8f7f25e

[laeubi]

This was seen with

Version: 2024-12 M1 (4.34.0 M1)
Build id: 20241003-0706