Finalizer should be shared eagerly

Author: eregon

src/main/java/org/truffleruby/core/FinalizationService.java

@@ -104,7 +104,6 @@ public FinalizationService(RubyContext context, ReferenceProcessor referenceProc
     }
 
     public synchronized FinalizerReference addFinalizer(Object object, FinalizerReference finalizerReference, Class<?> owner, Runnable action, DynamicObject root) {
-
         if (finalizerReference == null) {
             finalizerReference = new FinalizerReference(object, referenceProcessor.processingQueue, this);
             add(finalizerReference);

src/main/java/org/truffleruby/core/objectspace/ObjectSpaceNodes.java

@@ -35,6 +35,7 @@
 import org.truffleruby.language.objects.ReadObjectFieldNodeGen;
 import org.truffleruby.language.objects.WriteObjectFieldNode;
 import org.truffleruby.language.objects.WriteObjectFieldNodeGen;
+import org.truffleruby.language.objects.shared.WriteBarrierNode;
 
 @CoreClass("ObjectSpace")
 public abstract class ObjectSpaceNodes {
@@ -175,8 +176,14 @@ public abstract static class DefineFinalizerNode extends CoreMethodArrayArgument
 
         @Specialization
         public DynamicObject defineFinalizer(VirtualFrame frame, DynamicObject object, Object finalizer,
-                @Cached("create()") BranchProfile errorProfile) {
+                @Cached("create()") BranchProfile errorProfile,
+                @Cached("create()") WriteBarrierNode writeBarrierNode) {
             if (respondToCallNode.doesRespondTo(frame, "call", finalizer)) {
+                if (getContext().getSharedObjects().isSharing()) {
+                    // Share the finalizer, as it might run on a different Thread
+                    writeBarrierNode.executeWriteBarrier(finalizer);
+                }
+
                 defineFinalizer(object, finalizer);
                 Object[] objects = new Object[] { 0, finalizer };
                 return createArray(objects, objects.length);