Implement actor dummy object gc in java (ray-project#3822)

* Add dummy object gc in java

* Fix

* Address comments.

* Refine

* Address comments.

java/api/src/main/java/org/ray/api/runtime/RayRuntime.java

@@ -81,7 +81,7 @@ public interface RayRuntime {
  * @param args The arguments of the remote function.
  * @return The result object.
  */
- RayObject call(RayFunc func, RayActor actor, Object[] args);
+ RayObject call(RayFunc func, RayActor<?> actor, Object[] args);
 
  /**
  * Create an actor on a remote node.

java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java

@@ -221,16 +221,17 @@ public RayObject call(RayFunc func, Object[] args, CallOptions options) {
  }
 
  @Override
- public RayObject call(RayFunc func, RayActor actor, Object[] args) {
+ public RayObject call(RayFunc func, RayActor<?> actor, Object[] args) {
  if (!(actor instanceof RayActorImpl)) {
  throw new IllegalArgumentException("Unsupported actor type: " + actor.getClass().getName());
  }
- RayActorImpl actorImpl = (RayActorImpl)actor;
+ RayActorImpl<?> actorImpl = (RayActorImpl) actor;
  TaskSpec spec;
  synchronized (actor) {
  spec = createTaskSpec(func, actorImpl, args, false, null);
  spec.getExecutionDependencies().add(((RayActorImpl) actor).getTaskCursor());
  actorImpl.setTaskCursor(spec.returnIds[1]);
+ actorImpl.clearNewActorHandles();
  }
  rayletClient.submitTask(spec);
  return new RayObjectImpl(spec.returnIds[0]);
@@ -257,7 +258,7 @@ public <T> RayActor<T> createActor(RayFunc actorFactoryFunc,
  * @param isActorCreationTask Whether this task is an actor creation task.
  * @return A TaskSpec object.
  */
- private TaskSpec createTaskSpec(RayFunc func, RayActorImpl actor, Object[] args,
+ private TaskSpec createTaskSpec(RayFunc func, RayActorImpl<?> actor, Object[] args,
  boolean isActorCreationTask, BaseTaskOptions taskOptions) {
  UniqueId taskId = rayletClient.generateTaskId(workerContext.getCurrentDriverId(),
  workerContext.getCurrentTaskId(), workerContext.nextTaskIndex());
@@ -285,7 +286,9 @@ private TaskSpec createTaskSpec(RayFunc func, RayActorImpl actor, Object[] args,
  if (taskOptions instanceof ActorCreationOptions) {
  maxActorReconstruction = ((ActorCreationOptions) taskOptions).maxReconstructions;
  }
+
  RayFunction rayFunction = functionManager.getFunction(workerContext.getCurrentDriverId(), func);
+
  return new TaskSpec(
  workerContext.getCurrentDriverId(),
  taskId,
@@ -296,6 +299,7 @@ private TaskSpec createTaskSpec(RayFunc func, RayActorImpl actor, Object[] args,
  actor.getId(),
  actor.getHandleId(),
  actor.increaseTaskCounter(),
+ actor.getNewActorHandles().toArray(new UniqueId[0]),
  ArgumentsBuilder.wrap(args),
  returnIds,
  resources,

java/runtime/src/main/java/org/ray/runtime/RayActorImpl.java

@@ -4,6 +4,8 @@
 import java.io.IOException;
 import java.io.ObjectInput;
 import java.io.ObjectOutput;
+import java.util.ArrayList;
+import java.util.List;
 import org.ray.api.RayActor;
 import org.ray.api.id.UniqueId;
 import org.ray.runtime.util.Sha1Digestor;
@@ -29,6 +31,14 @@ public final class RayActorImpl<T> implements RayActor<T>, Externalizable {
  */
  private int numForks;
 
+ /**
+ * The new actor handles that were created from this handle
+ * since the last task on this handle was submitted. This is
+ * used to garbage-collect dummy objects that are no longer
+ * necessary in the backend.
+ */
+ private List<UniqueId> newActorHandles;
+
  public RayActorImpl() {
  this(UniqueId.NIL, UniqueId.NIL);
  }
@@ -42,6 +52,7 @@ public RayActorImpl(UniqueId id, UniqueId handleId) {
  this.handleId = handleId;
  this.taskCounter = 0;
  this.taskCursor = null;
+ this.newActorHandles = new ArrayList<>();
  numForks = 0;
  }
 
@@ -59,6 +70,14 @@ public void setTaskCursor(UniqueId taskCursor) {
  this.taskCursor = taskCursor;
  }
 
+ public List<UniqueId> getNewActorHandles() {
+ return this.newActorHandles;
+ }
+
+ public void clearNewActorHandles() {
+ this.newActorHandles.clear();
+ }
+
  public UniqueId getTaskCursor() {
  return taskCursor;
  }
@@ -74,6 +93,7 @@ public RayActorImpl<T> fork() {
  ret.numForks = 0;
  ret.taskCursor = this.taskCursor;
  ret.handleId = this.computeNextActorHandleId();
+ newActorHandles.add(ret.handleId);
  return ret;
  }
 

java/runtime/src/main/java/org/ray/runtime/raylet/RayletClientImpl.java

@@ -142,6 +142,11 @@ private static TaskSpec parseTaskSpecFromFlatbuffer(ByteBuffer bb) {
  UniqueId actorId = UniqueId.fromByteBuffer(info.actorIdAsByteBuffer());
  UniqueId actorHandleId = UniqueId.fromByteBuffer(info.actorHandleIdAsByteBuffer());
  int actorCounter = info.actorCounter();
+
+ // Deserialize new actor handles
+ UniqueId[] newActorHandles = UniqueIdUtil.getUniqueIdsFromByteBuffer(
+ info.newActorHandlesAsByteBuffer());
+
  // Deserialize args
  FunctionArg[] args = new FunctionArg[info.argsLength()];
  for (int i = 0; i < info.argsLength(); i++) {
@@ -175,7 +180,7 @@ private static TaskSpec parseTaskSpecFromFlatbuffer(ByteBuffer bb) {
  info.functionDescriptor(0), info.functionDescriptor(1), info.functionDescriptor(2)
  );
  return new TaskSpec(driverId, taskId, parentTaskId, parentCounter, actorCreationId,
- maxActorReconstructions, actorId, actorHandleId, actorCounter,
+ maxActorReconstructions, actorId, actorHandleId, actorCounter, newActorHandles,
  args, returnIds, resources, functionDescriptor);
  }
 

java/runtime/src/main/java/org/ray/runtime/task/TaskSpec.java

@@ -68,8 +68,8 @@ public boolean isActorCreationTask() {
 
  public TaskSpec(UniqueId driverId, UniqueId taskId, UniqueId parentTaskId, int parentCounter,
  UniqueId actorCreationId, int maxActorReconstructions, UniqueId actorId,
- UniqueId actorHandleId, int actorCounter, FunctionArg[] args, UniqueId[] returnIds,
- Map<String, Double> resources, FunctionDescriptor functionDescriptor) {
+ UniqueId actorHandleId, int actorCounter, UniqueId[] newActorHandles, FunctionArg[] args,
+ UniqueId[] returnIds, Map<String, Double> resources, FunctionDescriptor functionDescriptor) {
  this.driverId = driverId;
  this.taskId = taskId;
  this.parentTaskId = parentTaskId;
@@ -79,8 +79,7 @@ public TaskSpec(UniqueId driverId, UniqueId taskId, UniqueId parentTaskId, int p
  this.actorId = actorId;
  this.actorHandleId = actorHandleId;
  this.actorCounter = actorCounter;
- // TODO: Initialize the new actor handles.
- this.newActorHandles = new UniqueId[] {};
+ this.newActorHandles = newActorHandles;
  this.args = args;
  this.returnIds = returnIds;
  this.resources = resources;