Update !vthread command to use GC continuation list

Fixes #17084

Signed-off-by: Gengchen Tuo <[email protected]>

debugtools/DDR_VM/src/com/ibm/j9ddr/AuxFieldInfo29.dat

@@ -267,7 +267,6 @@ J9JavaVM.jitConfig = required
 J9JavaVM.jniGlobalReferences = required
 J9JavaVM.jniWeakGlobalReferences = required
 J9JavaVM.jvmtiData = required
-J9JavaVM.liveVirtualThreadList = J9Object**
 J9JavaVM.longArrayClass = required
 J9JavaVM.longReflectClass = required
 J9JavaVM.mainThread = required
@@ -286,7 +285,6 @@ J9JavaVM.sharedInvariantInternTable = required
 J9JavaVM.shortReflectClass = required
 J9JavaVM.systemClassLoader = required
 J9JavaVM.systemProperties = required
-J9JavaVM.virtualThreadLinkNextOffset = UDATA
 J9JavaVM.vmArgsArray = required
 J9JavaVM.voidReflectClass = required
 J9LineNumber.lineNumber = required
@@ -625,12 +623,15 @@ MM_AllocationContextTarok._allocationContextType = required
 MM_CardTable._cardTableStart = required
 MM_CardTable._cardTableVirtualStart = required
 MM_CardTable._heapBase = required
+MM_ContinuationObjectList._head = J9Object*
+MM_ContinuationObjectList._nextList = MM_ContinuationObjectList*
 MM_CopyScanCache.cacheAlloc = required
 MM_CopyScanCache.cacheTop = required
 MM_EnvironmentStandard._survivorCopyScanCache = required
 MM_EnvironmentStandard._tenureCopyScanCache = required
 MM_GCExtensions.accessBarrier = required
 MM_GCExtensions.collectStringConstants = required
+MM_GCExtensions.continuationObjectLists = MM_ContinuationObjectList*
 MM_GCExtensions.dynamicClassUnloading = required
 MM_GCExtensions.finalizeListManager = required
 MM_GCExtensions.ownableSynchronizerObjectLists = required
@@ -713,6 +714,7 @@ MM_MemorySpace._name = required
 MM_MemorySubSpace._memorySpace = required
 MM_MemorySubSpace._memoryType = required
 MM_MemorySubSpaceGeneric._memoryPool = required
+MM_ObjectAccessBarrier._continuationLinkOffset = UDATA
 MM_ObjectAccessBarrier._ownableSynchronizerLinkOffset = required
 MM_ObjectAccessBarrier._referenceLinkOffset = required
 MM_OwnableSynchronizerObjectList._head = required

debugtools/DDR_VM/src/com/ibm/j9ddr/vm29/tools/ddrinteractive/VirtualThreadsCommand.java

@@ -29,10 +29,12 @@
 import com.ibm.j9ddr.tools.ddrinteractive.DDRInteractiveCommandException;
 import com.ibm.j9ddr.vm29.j9.DataType;
 import com.ibm.j9ddr.vm29.j9.J9ObjectFieldOffset;
+import com.ibm.j9ddr.vm29.j9.gc.GCBase;
 import com.ibm.j9ddr.vm29.pointer.ObjectReferencePointer;
-import com.ibm.j9ddr.vm29.pointer.PointerPointer;
 import com.ibm.j9ddr.vm29.pointer.generated.J9JavaVMPointer;
 import com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer;
+import com.ibm.j9ddr.vm29.pointer.generated.MM_ContinuationObjectListPointer;
+import com.ibm.j9ddr.vm29.pointer.generated.MM_GCExtensionsPointer;
 import com.ibm.j9ddr.vm29.pointer.helper.J9ObjectHelper;
 import com.ibm.j9ddr.vm29.pointer.helper.J9RASHelper;
 import com.ibm.j9ddr.vm29.types.UDATA;
@@ -49,6 +51,31 @@
  *     ...
  */
 public class VirtualThreadsCommand extends Command {
+	private static J9ObjectFieldOffset vthreadOffset;
+	private static J9ObjectFieldOffset vmRefOffset;
+	private static J9ObjectFieldOffset nameOffset;
+
+	private static J9ObjectPointer getVirtualThread(J9ObjectPointer continuation) throws CorruptDataException {
+		if (vthreadOffset == null) {
+			vthreadOffset = J9ObjectHelper.getFieldOffset(continuation, "vthread", "Ljava/lang/Thread;");
+		}
+		return J9ObjectHelper.getObjectField(continuation, vthreadOffset);
+	}
+
+	private static long getVmRef(J9ObjectPointer continuation) throws CorruptDataException {
+		if (vmRefOffset == null) {
+			vmRefOffset = J9ObjectHelper.getFieldOffset(continuation, "vmRef", "J");
+		}
+		return J9ObjectHelper.getLongField(continuation, vmRefOffset);
+	}
+
+	private static J9ObjectPointer getName(J9ObjectPointer vthread) throws CorruptDataException {
+		if (nameOffset == null) {
+			nameOffset = J9ObjectHelper.getFieldOffset(vthread, "name", "Ljava/lang/String;");
+		}
+		return J9ObjectHelper.getObjectField(vthread, nameOffset);
+	}
+
 	public VirtualThreadsCommand() {
 		addCommand("vthreads", "", "Lists virtual threads");
 	}
@@ -72,43 +99,31 @@ public void run(String command, String[] args, Context context, PrintStream out)
 	 * @param out the PrintStream to write output to
 	 */
 	private static void displayVirtualThreads(J9JavaVMPointer vm, PrintStream out) throws CorruptDataException, NoSuchFieldException {
-		PointerPointer mainVirtualThread = vm.liveVirtualThreadList();
-		if (mainVirtualThread.isNull()) {
-			return;
-		}
-
-		J9ObjectPointer root = J9ObjectPointer.cast(mainVirtualThread.at(0));
-		if (root.isNull()) {
-			return;
-		}
-
-		UDATA linkNextOffset = vm.virtualThreadLinkNextOffset();
-		/*
-		 * liveVirtualThreadList is a circular doubly-linked list storing all the live virtual threads.
-		 * The root node is a dummy virtual thread marking the start and the end of the list.
-		 */
-		J9ObjectPointer node = ObjectReferencePointer.cast(root.addOffset(linkNextOffset)).at(0);
-		J9ObjectFieldOffset nameOffset = J9ObjectHelper.getFieldOffset(node, "name", "Ljava/lang/String;");
-		J9ObjectFieldOffset contOffset = J9ObjectHelper.getFieldOffset(node, "cont", "Ljdk/internal/vm/Continuation;");
-		J9ObjectPointer cont = J9ObjectHelper.getObjectField(node, contOffset);
-		J9ObjectFieldOffset vmRefOffset = J9ObjectHelper.getFieldOffset(cont, "vmRef", "J");
-
 		String addressFormat = "0x%0" + (UDATA.SIZEOF * 2) + "x";
 		String outputFormat = "!continuationstack " + addressFormat
 				+ " !j9vmcontinuation " + addressFormat
 				+ " !j9object %s (Continuation) !j9object %s (VThread) - %s%n";
-		while (!node.eq(root)) {
-			J9ObjectPointer name = J9ObjectHelper.getObjectField(node, nameOffset);
-			cont = J9ObjectHelper.getObjectField(node, contOffset);
-			long vmRef = J9ObjectHelper.getLongField(cont, vmRefOffset);
-			out.format(
-					outputFormat,
-					vmRef,
-					vmRef,
-					cont.getHexAddress(),
-					node.getHexAddress(),
-					J9ObjectHelper.stringValue(name));
-			node = ObjectReferencePointer.cast(node.addOffset(linkNextOffset)).at(0);
+		MM_GCExtensionsPointer extensions = GCBase.getExtensions();
+		UDATA linkOffset = extensions.accessBarrier()._continuationLinkOffset();
+		MM_ContinuationObjectListPointer continuationObjectList = extensions.continuationObjectLists();
+
+		while (continuationObjectList.notNull()) {
+			J9ObjectPointer continuation = continuationObjectList._head();
+			while (continuation.notNull()) {
+				long vmRef = getVmRef(continuation);
+				J9ObjectPointer vthread = getVirtualThread(continuation);
+				J9ObjectPointer name = getName(vthread);
+
+				out.format(
+						outputFormat,
+						vmRef,
+						vmRef,
+						continuation.getHexAddress(),
+						vthread.getHexAddress(),
+						J9ObjectHelper.stringValue(name));
+				continuation = ObjectReferencePointer.cast(continuation.addOffset(linkOffset)).at(0);
+			}
+			continuationObjectList = continuationObjectList._nextList();
 		}
 	}
 }

runtime/rasdump/trigger.c

@@ -681,6 +681,7 @@ prepareForDump(struct J9JavaVM *vm, struct J9RASdumpAgent *agent, struct J9RASdu
 		/* If exclusive access has been obtained, do the requested preparation */
 		if (newState & J9RAS_DUMP_GOT_EXCLUSIVE_VM_ACCESS) {
 			vm->memoryManagerFunctions->j9gc_flush_caches_for_walk(vm);
+			vm->memoryManagerFunctions->j9gc_flush_nonAllocationCaches_for_walk(vm);
 			newState |= J9RAS_DUMP_HEAP_PREPARED;
 		}
 	}