diff --git a/java/api/src/main/java/org/ray/api/RayActor.java b/java/api/src/main/java/org/ray/api/RayActor.java
index 8d44901ea..0c1a7bd84 100644
--- a/java/api/src/main/java/org/ray/api/RayActor.java
+++ b/java/api/src/main/java/org/ray/api/RayActor.java
@@ -14,10 +14,4 @@ public interface RayActor<T> {
    * @return The id of this actor.
    */
   ActorId getId();
-
-  /**
-   * @return The id of this actor handle.
-   */
-  UniqueId getHandleId();
-
 }
diff --git a/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java b/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java
index be7c4e471..9c39e7a2a 100644
--- a/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java
+++ b/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java
@@ -165,7 +165,8 @@ public abstract class AbstractRayRuntime implements RayRuntime {
 
   private RayObject callNormalFunction(FunctionDescriptor functionDescriptor,
       Object[] args, int numReturns, CallOptions options) {
-    List<FunctionArg> functionArgs = ArgumentsBuilder.wrap(args, /*isDirectCall*/false);
+    List<FunctionArg> functionArgs = ArgumentsBuilder
+        .wrap(args, functionDescriptor.getLanguage(), /*isDirectCall*/false);
     List<ObjectId> returnIds = taskSubmitter.submitTask(functionDescriptor,
         functionArgs, numReturns, options);
     Preconditions.checkState(returnIds.size() == numReturns && returnIds.size() <= 1);
@@ -178,7 +179,8 @@ public abstract class AbstractRayRuntime implements RayRuntime {
 
   private RayObject callActorFunction(RayActor rayActor,
       FunctionDescriptor functionDescriptor, Object[] args, int numReturns) {
-    List<FunctionArg> functionArgs = ArgumentsBuilder.wrap(args, isDirectCall(rayActor));
+    List<FunctionArg> functionArgs = ArgumentsBuilder
+        .wrap(args, functionDescriptor.getLanguage(), isDirectCall(rayActor));
     List<ObjectId> returnIds = taskSubmitter.submitActorTask(rayActor,
         functionDescriptor, functionArgs, numReturns, null);
     Preconditions.checkState(returnIds.size() == numReturns && returnIds.size() <= 1);
@@ -191,7 +193,8 @@ public abstract class AbstractRayRuntime implements RayRuntime {
 
   private RayActor createActorImpl(FunctionDescriptor functionDescriptor,
       Object[] args, ActorCreationOptions options) {
-    List<FunctionArg> functionArgs = ArgumentsBuilder.wrap(args, /*isDirectCall*/false);
+    List<FunctionArg> functionArgs = ArgumentsBuilder
+        .wrap(args, functionDescriptor.getLanguage(),  /*isDirectCall*/false);
     if (functionDescriptor.getLanguage() != Language.JAVA && options != null) {
       Preconditions.checkState(Strings.isNullOrEmpty(options.jvmOptions));
     }
diff --git a/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java b/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java
index 56002a595..4775553c5 100644
--- a/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java
+++ b/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java
@@ -109,6 +109,7 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
     // TODO(qwang): Get object_store_socket_name and raylet_socket_name from Redis.
     nativeCoreWorkerPointer = nativeInitCoreWorker(rayConfig.workerMode.getNumber(),
         rayConfig.objectStoreSocketName, rayConfig.rayletSocketName,
+        rayConfig.nodeIp, rayConfig.getNodeManagerPort(),
         (rayConfig.workerMode == WorkerType.DRIVER ? rayConfig.getJobId() : JobId.NIL).getBytes(),
         new GcsClientOptions(rayConfig));
     Preconditions.checkState(nativeCoreWorkerPointer != 0);
@@ -150,6 +151,10 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
     nativeRunTaskExecutor(nativeCoreWorkerPointer, taskExecutor);
   }
 
+  public long getNativeCoreWorkerPointer() {
+    return nativeCoreWorkerPointer;
+  }
+
   /**
    * Register this worker or driver to GCS.
    */
@@ -176,7 +181,8 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
   }
 
   private static native long nativeInitCoreWorker(int workerMode, String storeSocket,
-      String rayletSocket, byte[] jobId, GcsClientOptions gcsClientOptions);
+      String rayletSocket, String nodeIpAddress, int nodeManagerPort, byte[] jobId,
+      GcsClientOptions gcsClientOptions);
 
   private static native void nativeRunTaskExecutor(long nativeCoreWorkerPointer,
       TaskExecutor taskExecutor);
diff --git a/java/runtime/src/main/java/org/ray/runtime/actor/LocalModeRayActor.java b/java/runtime/src/main/java/org/ray/runtime/actor/LocalModeRayActor.java
index 4ffe36d3d..f8bca58c9 100644
--- a/java/runtime/src/main/java/org/ray/runtime/actor/LocalModeRayActor.java
+++ b/java/runtime/src/main/java/org/ray/runtime/actor/LocalModeRayActor.java
@@ -35,11 +35,6 @@ public class LocalModeRayActor implements RayActor, Externalizable {
     return actorId;
   }
 
-  @Override
-  public UniqueId getHandleId() {
-    return UniqueId.NIL;
-  }
-
   public ObjectId exchangePreviousActorTaskDummyObjectId(ObjectId previousActorTaskDummyObjectId) {
     return this.previousActorTaskDummyObjectId.getAndSet(previousActorTaskDummyObjectId);
   }
diff --git a/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActor.java b/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActor.java
index 8dd7ac8c3..a4d7c31b9 100644
--- a/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActor.java
+++ b/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActor.java
@@ -6,10 +6,15 @@ import java.io.IOException;
 import java.io.ObjectInput;
 import java.io.ObjectOutput;
 import java.util.List;
+import org.ray.api.Ray;
 import org.ray.api.RayActor;
 import org.ray.api.RayPyActor;
 import org.ray.api.id.ActorId;
 import org.ray.api.id.UniqueId;
+import org.ray.api.runtime.RayRuntime;
+import org.ray.runtime.AbstractRayRuntime;
+import org.ray.runtime.RayNativeRuntime;
+import org.ray.runtime.RayMultiWorkerNativeRuntime;
 import org.ray.runtime.generated.Common.Language;
 
 /**
@@ -18,13 +23,19 @@ import org.ray.runtime.generated.Common.Language;
 public class NativeRayActor implements RayActor, RayPyActor, Externalizable {
 
   /**
-   * Address of native actor handle.
+   * Address of core worker.
    */
-  private long nativeActorHandle;
+  private long nativeCoreWorkerPointer;  
+  /**
+   * ID of the actor.
+   */
+  private byte[] actorId;
 
-  public NativeRayActor(long nativeActorHandle) {
-    Preconditions.checkState(nativeActorHandle != 0);
-    this.nativeActorHandle = nativeActorHandle;
+  public NativeRayActor(long nativeCoreWorkerPointer, byte[] actorId) {
+    Preconditions.checkState(nativeCoreWorkerPointer != 0);
+    Preconditions.checkState(!ActorId.fromBytes(actorId).isNil());
+    this.nativeCoreWorkerPointer = nativeCoreWorkerPointer;
+    this.actorId = actorId;
   }
 
   /**
@@ -33,75 +44,64 @@ public class NativeRayActor implements RayActor, RayPyActor, Externalizable {
   public NativeRayActor() {
   }
 
-  public long getNativeActorHandle() {
-    return nativeActorHandle;
-  }
-
   @Override
   public ActorId getId() {
-    return ActorId.fromBytes(nativeGetActorId(nativeActorHandle));
-  }
-
-  @Override
-  public UniqueId getHandleId() {
-    return new UniqueId(nativeGetActorHandleId(nativeActorHandle));
+    return ActorId.fromBytes(actorId);
   }
 
   public Language getLanguage() {
-    return Language.forNumber(nativeGetLanguage(nativeActorHandle));
+    return Language.forNumber(nativeGetLanguage(nativeCoreWorkerPointer, actorId));
   }
 
   public boolean isDirectCallActor() {
-    return nativeIsDirectCallActor(nativeActorHandle);
+    return nativeIsDirectCallActor(nativeCoreWorkerPointer, actorId);
   }
 
   @Override
   public String getModuleName() {
     Preconditions.checkState(getLanguage() == Language.PYTHON);
-    return nativeGetActorCreationTaskFunctionDescriptor(nativeActorHandle).get(0);
+    return nativeGetActorCreationTaskFunctionDescriptor(
+      nativeCoreWorkerPointer, actorId).get(0);
   }
 
   @Override
   public String getClassName() {
     Preconditions.checkState(getLanguage() == Language.PYTHON);
-    return nativeGetActorCreationTaskFunctionDescriptor(nativeActorHandle).get(1);
-  }
-
-  public NativeRayActor fork() {
-    return new NativeRayActor(nativeFork(nativeActorHandle));
+    return nativeGetActorCreationTaskFunctionDescriptor(
+      nativeCoreWorkerPointer, actorId).get(1);
   }
 
   @Override
   public void writeExternal(ObjectOutput out) throws IOException {
-    out.writeObject(nativeSerialize(nativeActorHandle));
+    out.writeObject(nativeSerialize(nativeCoreWorkerPointer, actorId));
   }
 
   @Override
   public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
-    nativeActorHandle = nativeDeserialize((byte[]) in.readObject());
+    RayRuntime runtime = Ray.internal();
+    if (runtime instanceof RayMultiWorkerNativeRuntime) {
+      runtime = ((RayMultiWorkerNativeRuntime) runtime).getCurrentRuntime();
+    }
+    
+    Preconditions.checkState(runtime instanceof RayNativeRuntime);
+    nativeCoreWorkerPointer = ((RayNativeRuntime)runtime).getNativeCoreWorkerPointer();
+
+    actorId = nativeDeserialize(nativeCoreWorkerPointer, (byte[]) in.readObject());
   }
 
   @Override
   protected void finalize() {
-    nativeFree(nativeActorHandle);
+    // TODO(zhijunfu): do we need to free the ActorHandle in core worker?
   }
 
-  private static native long nativeFork(long nativeActorHandle);
+  private static native int nativeGetLanguage(long nativeCoreWorkerPointer, byte[] actorId);
 
-  private static native byte[] nativeGetActorId(long nativeActorHandle);
-
-  private static native byte[] nativeGetActorHandleId(long nativeActorHandle);
-
-  private static native int nativeGetLanguage(long nativeActorHandle);
-
-  private static native boolean nativeIsDirectCallActor(long nativeActorHandle);
+  private static native boolean nativeIsDirectCallActor(long nativeCoreWorkerPointer, byte[] actorId);
 
   private static native List<String> nativeGetActorCreationTaskFunctionDescriptor(
-      long nativeActorHandle);
+    long nativeCoreWorkerPointer, byte[] actorId);
 
-  private static native byte[] nativeSerialize(long nativeActorHandle);
+  private static native byte[] nativeSerialize(long nativeCoreWorkerPointer, byte[] actorId);
 
-  private static native long nativeDeserialize(byte[] data);
-
-  private static native void nativeFree(long nativeActorHandle);
+  private static native byte[] nativeDeserialize(long nativeCoreWorkerPointer, byte[] data);
 }
diff --git a/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActorSerializer.java b/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActorSerializer.java
index 11102cdd8..45a3b932d 100644
--- a/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActorSerializer.java
+++ b/java/runtime/src/main/java/org/ray/runtime/actor/NativeRayActorSerializer.java
@@ -15,7 +15,7 @@ public class NativeRayActorSerializer extends FSTBasicObjectSerializer {
   @Override
   public void writeObject(FSTObjectOutput out, Object toWrite, FSTClazzInfo clzInfo,
       FSTClazzInfo.FSTFieldInfo referencedBy, int streamPosition) throws IOException {
-    ((NativeRayActor) toWrite).fork().writeExternal(out);
+    ((NativeRayActor) toWrite).writeExternal(out);
   }
 
   @Override
diff --git a/java/runtime/src/main/java/org/ray/runtime/config/RayConfig.java b/java/runtime/src/main/java/org/ray/runtime/config/RayConfig.java
index 3be4bee26..27aec4ce8 100644
--- a/java/runtime/src/main/java/org/ray/runtime/config/RayConfig.java
+++ b/java/runtime/src/main/java/org/ray/runtime/config/RayConfig.java
@@ -52,6 +52,7 @@ public class RayConfig {
   public final Long objectStoreSize;
 
   public final String rayletSocketName;
+  private int nodeManagerPort;
   public final List<String> rayletConfigParameters;
 
   public final String jobResourcePath;
@@ -154,11 +155,18 @@ public class RayConfig {
 
     // Raylet socket name.
     rayletSocketName = config.getString("ray.raylet.socket-name");
+    // Raylet node manager port.
+    nodeManagerPort = config.getInt("ray.raylet.node-manager-port");
+    if (nodeManagerPort == 0) {
+      Preconditions.checkState(this.redisAddress == null,
+          "Java worker started by raylet should accept the node manager port from raylet.");
+      nodeManagerPort = NetworkUtil.getUnusedPort();
+    }
 
     // Raylet parameters.
     rayletConfigParameters = new ArrayList<>();
     Config rayletConfig = config.getConfig("ray.raylet.config");
-    for (Map.Entry<String,ConfigValue> entry : rayletConfig.entrySet()) {
+    for (Map.Entry<String, ConfigValue> entry : rayletConfig.entrySet()) {
       String parameter = entry.getKey() + "," + entry.getValue().unwrapped();
       rayletConfigParameters.add(parameter);
     }
@@ -211,6 +219,10 @@ public class RayConfig {
     return this.jobId;
   }
 
+  public int getNodeManagerPort() {
+    return nodeManagerPort;
+  }
+
   @Override
   public String toString() {
     return "RayConfig{"
@@ -243,7 +255,7 @@ public class RayConfig {
    * 1. System properties.
    * 2. `ray.conf` file.
    * 3. `ray.default.conf` file.
-  */
+   */
   public static RayConfig create() {
     ConfigFactory.invalidateCaches();
     Config config = ConfigFactory.systemProperties();
diff --git a/java/runtime/src/main/java/org/ray/runtime/runner/RunManager.java b/java/runtime/src/main/java/org/ray/runtime/runner/RunManager.java
index 7434e3890..f1bfab1f1 100644
--- a/java/runtime/src/main/java/org/ray/runtime/runner/RunManager.java
+++ b/java/runtime/src/main/java/org/ray/runtime/runner/RunManager.java
@@ -258,7 +258,7 @@ public class RunManager {
           String.format("--raylet_socket_name=%s", rayConfig.rayletSocketName),
           String.format("--store_socket_name=%s", rayConfig.objectStoreSocketName),
           String.format("--object_manager_port=%d", 0), // The object manager port.
-          String.format("--node_manager_port=%d", 0),  // The node manager port.
+          String.format("--node_manager_port=%d", rayConfig.getNodeManagerPort()),  // The node manager port.
           String.format("--node_ip_address=%s", rayConfig.nodeIp),
           String.format("--redis_address=%s", rayConfig.getRedisIp()),
           String.format("--redis_port=%d", rayConfig.getRedisPort()),
@@ -312,6 +312,8 @@ public class RunManager {
     cmd.add("-Dray.raylet.socket-name=" + rayConfig.rayletSocketName);
     cmd.add("-Dray.object-store.socket-name=" + rayConfig.objectStoreSocketName);
 
+    cmd.add("-Dray.raylet.node-manager-port=" + rayConfig.getNodeManagerPort());
+
     // Config overwrite
     cmd.add("-Dray.redis.address=" + rayConfig.getRedisAddress());
 
@@ -337,7 +339,7 @@ public class RunManager {
 
   private void startObjectStore() {
     try (FileUtil.TempFile plasmaStoreFile = FileUtil
-        .getTempFileFromResource("plasma_store_server")) {
+        .getTempFileFromResource("external/plasma/plasma_store_server")) {
       plasmaStoreFile.getFile().setExecutable(true);
       List<String> command = ImmutableList.of(
           // The plasma store executable file.
diff --git a/java/runtime/src/main/java/org/ray/runtime/task/ArgumentsBuilder.java b/java/runtime/src/main/java/org/ray/runtime/task/ArgumentsBuilder.java
index 07ae3dfb1..978a5a56b 100644
--- a/java/runtime/src/main/java/org/ray/runtime/task/ArgumentsBuilder.java
+++ b/java/runtime/src/main/java/org/ray/runtime/task/ArgumentsBuilder.java
@@ -8,6 +8,7 @@ import org.ray.api.id.ObjectId;
 import org.ray.api.runtime.RayRuntime;
 import org.ray.runtime.AbstractRayRuntime;
 import org.ray.runtime.RayMultiWorkerNativeRuntime;
+import org.ray.runtime.generated.Common.Language;
 import org.ray.runtime.object.NativeRayObject;
 import org.ray.runtime.object.ObjectSerializer;
 
@@ -22,10 +23,16 @@ public class ArgumentsBuilder {
    */
   private static final int LARGEST_SIZE_PASS_BY_VALUE = 100 * 1024;
 
+  /**
+   * This dummy type is also defined in signature.py. Please keep it synced.
+   */
+  private static final NativeRayObject PYTHON_DUMMY_TYPE = ObjectSerializer
+      .serialize("__RAY_DUMMY__".getBytes());
+
   /**
    * Convert real function arguments to task spec arguments.
    */
-  public static List<FunctionArg> wrap(Object[] args, boolean isDirectCall) {
+  public static List<FunctionArg> wrap(Object[] args, Language language, boolean isDirectCall) {
     List<FunctionArg> ret = new ArrayList<>();
     for (Object arg : args) {
       ObjectId id = null;
@@ -48,6 +55,9 @@ public class ArgumentsBuilder {
           value = null;
         }
       }
+      if (language == Language.PYTHON) {
+        ret.add(FunctionArg.passByValue(PYTHON_DUMMY_TYPE));
+      }
       if (id != null) {
         ret.add(FunctionArg.passByReference(id));
       } else {
diff --git a/java/runtime/src/main/java/org/ray/runtime/task/NativeTaskSubmitter.java b/java/runtime/src/main/java/org/ray/runtime/task/NativeTaskSubmitter.java
index cae93e788..bc1083d9b 100644
--- a/java/runtime/src/main/java/org/ray/runtime/task/NativeTaskSubmitter.java
+++ b/java/runtime/src/main/java/org/ray/runtime/task/NativeTaskSubmitter.java
@@ -35,9 +35,9 @@ public class NativeTaskSubmitter implements TaskSubmitter {
   @Override
   public RayActor createActor(FunctionDescriptor functionDescriptor, List<FunctionArg> args,
       ActorCreationOptions options) {
-    long nativeActorHandle = nativeCreateActor(nativeCoreWorkerPointer, functionDescriptor, args,
+    byte[] actorId = nativeCreateActor(nativeCoreWorkerPointer, functionDescriptor, args,
         options);
-    return new NativeRayActor(nativeActorHandle);
+    return new NativeRayActor(nativeCoreWorkerPointer, actorId);
   }
 
   @Override
@@ -45,7 +45,7 @@ public class NativeTaskSubmitter implements TaskSubmitter {
       List<FunctionArg> args, int numReturns, CallOptions options) {
     Preconditions.checkState(actor instanceof NativeRayActor);
     List<byte[]> returnIds = nativeSubmitActorTask(nativeCoreWorkerPointer,
-        ((NativeRayActor) actor).getNativeActorHandle(), functionDescriptor, args, numReturns,
+        actor.getId().getBytes(), functionDescriptor, args, numReturns,
         options);
     return returnIds.stream().map(ObjectId::new).collect(Collectors.toList());
   }
@@ -54,11 +54,11 @@ public class NativeTaskSubmitter implements TaskSubmitter {
       FunctionDescriptor functionDescriptor, List<FunctionArg> args, int numReturns,
       CallOptions callOptions);
 
-  private static native long nativeCreateActor(long nativeCoreWorkerPointer,
+  private static native byte[] nativeCreateActor(long nativeCoreWorkerPointer,
       FunctionDescriptor functionDescriptor, List<FunctionArg> args,
       ActorCreationOptions actorCreationOptions);
 
   private static native List<byte[]> nativeSubmitActorTask(long nativeCoreWorkerPointer,
-      long nativeActorHandle, FunctionDescriptor functionDescriptor, List<FunctionArg> args,
+      byte[] actorId, FunctionDescriptor functionDescriptor, List<FunctionArg> args,
       int numReturns, CallOptions callOptions);
 }
diff --git a/java/runtime/src/main/java/org/ray/runtime/util/NetworkUtil.java b/java/runtime/src/main/java/org/ray/runtime/util/NetworkUtil.java
index 23875aba1..8a6aca3f3 100644
--- a/java/runtime/src/main/java/org/ray/runtime/util/NetworkUtil.java
+++ b/java/runtime/src/main/java/org/ray/runtime/util/NetworkUtil.java
@@ -5,6 +5,7 @@ import java.io.IOException;
 import java.net.DatagramSocket;
 import java.net.Inet6Address;
 import java.net.InetAddress;
+import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.util.Enumeration;
@@ -47,6 +48,19 @@ public class NetworkUtil {
     return "127.0.0.1";
   }
 
+  public static int getUnusedPort() {
+    int port;
+    try {
+      ServerSocket ss = new ServerSocket();
+      ss.bind(new InetSocketAddress(0));
+      port = ss.getLocalPort();
+      ss.close();
+    } catch (Exception e) {
+      throw new RuntimeException("Failed to bind to an available port.", e);
+    }
+    return port;
+  }
+
   public static boolean isPortAvailable(int port) {
     if (port < 1 || port > 65535) {
       throw new IllegalArgumentException("Invalid start port: " + port);
diff --git a/java/runtime/src/main/resources/ray.default.conf b/java/runtime/src/main/resources/ray.default.conf
index 3da6089d7..208a07b5a 100644
--- a/java/runtime/src/main/resources/ray.default.conf
+++ b/java/runtime/src/main/resources/ray.default.conf
@@ -84,6 +84,8 @@ ray {
   raylet {
     // RPC socket name of Raylet
     socket-name: /tmp/ray/sockets/raylet
+    // Listening port for node manager.
+    node-manager-port: 0
 
     // See src/ray/ray_config_def.h for options.
     config {
diff --git a/java/test/src/main/java/org/ray/api/test/ActorTest.java b/java/test/src/main/java/org/ray/api/test/ActorTest.java
index 8b1b441e4..5dd81443f 100644
--- a/java/test/src/main/java/org/ray/api/test/ActorTest.java
+++ b/java/test/src/main/java/org/ray/api/test/ActorTest.java
@@ -12,8 +12,6 @@ import org.ray.api.TestUtils.LargeObject;
 import org.ray.api.annotation.RayRemote;
 import org.ray.api.exception.UnreconstructableException;
 import org.ray.api.id.UniqueId;
-import org.ray.runtime.actor.NativeRayActor;
-import org.ray.runtime.object.NativeRayObject;
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
@@ -107,14 +105,6 @@ public class ActorTest extends BaseTest {
             .get());
   }
 
-  public void testForkingActorHandle() {
-    TestUtils.skipTestUnderSingleProcess();
-    RayActor<Counter> counter = Ray.createActor(Counter::new, 100);
-    Assert.assertEquals(Integer.valueOf(101), Ray.call(Counter::increaseAndGet, counter, 1).get());
-    RayActor<Counter> counter2 = ((NativeRayActor) counter).fork();
-    Assert.assertEquals(Integer.valueOf(103), Ray.call(Counter::increaseAndGet, counter2, 2).get());
-  }
-
   public void testUnreconstructableActorObject() throws InterruptedException {
     TestUtils.skipTestUnderSingleProcess();
     // The UnreconstructableException is created by raylet.
@@ -128,9 +118,9 @@ public class ActorTest extends BaseTest {
     Ray.internal().free(ImmutableList.of(value.getId()), false, false);
     // Wait until the object is deleted, because the above free operation is async.
     while (true) {
-      NativeRayObject result = TestUtils.getRuntime().getObjectStore()
-          .getRaw(ImmutableList.of(value.getId()), 0).get(0);
-      if (result == null) {
+      Boolean result = TestUtils.getRuntime().getObjectStore()
+          .wait(ImmutableList.of(value.getId()), 1, 0).get(0);
+      if (!result) {
         break;
       }
       TimeUnit.MILLISECONDS.sleep(100);
diff --git a/java/test/src/main/java/org/ray/api/test/BaseMultiLanguageTest.java b/java/test/src/main/java/org/ray/api/test/BaseMultiLanguageTest.java
index 995f9588a..294430492 100644
--- a/java/test/src/main/java/org/ray/api/test/BaseMultiLanguageTest.java
+++ b/java/test/src/main/java/org/ray/api/test/BaseMultiLanguageTest.java
@@ -10,6 +10,7 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.concurrent.TimeUnit;
 import org.ray.api.Ray;
+import org.ray.runtime.util.NetworkUtil;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.testng.SkipException;
@@ -65,6 +66,8 @@ public abstract class BaseMultiLanguageTest {
       }
     }
 
+    String nodeManagerPort = String.valueOf(NetworkUtil.getUnusedPort());
+
     // Start ray cluster.
     String workerOptions =
         " -classpath " + System.getProperty("java.class.path");
@@ -75,6 +78,7 @@ public abstract class BaseMultiLanguageTest {
         "--redis-port=6379",
         String.format("--plasma-store-socket-name=%s", PLASMA_STORE_SOCKET_NAME),
         String.format("--raylet-socket-name=%s", RAYLET_SOCKET_NAME),
+        String.format("--node-manager-port=%s", nodeManagerPort),
         "--load-code-from-local",
         "--include-java",
         "--java-worker-options=" + workerOptions
@@ -94,6 +98,7 @@ public abstract class BaseMultiLanguageTest {
     System.setProperty("ray.redis.address", "127.0.0.1:6379");
     System.setProperty("ray.object-store.socket-name", PLASMA_STORE_SOCKET_NAME);
     System.setProperty("ray.raylet.socket-name", RAYLET_SOCKET_NAME);
+    System.setProperty("ray.raylet.node-manager-port", nodeManagerPort);
     Ray.init();
   }
 
@@ -113,6 +118,7 @@ public abstract class BaseMultiLanguageTest {
     System.clearProperty("ray.redis.address");
     System.clearProperty("ray.object-store.socket-name");
     System.clearProperty("ray.raylet.socket-name");
+    System.clearProperty("ray.raylet.node-manager-port");
 
     // Stop ray cluster.
     final List<String> stopCommand = ImmutableList.of(
diff --git a/java/test/src/main/java/org/ray/api/test/PlasmaFreeTest.java b/java/test/src/main/java/org/ray/api/test/PlasmaFreeTest.java
index 395209ad5..9a125fabf 100644
--- a/java/test/src/main/java/org/ray/api/test/PlasmaFreeTest.java
+++ b/java/test/src/main/java/org/ray/api/test/PlasmaFreeTest.java
@@ -26,7 +26,7 @@ public class PlasmaFreeTest extends BaseTest {
 
     final boolean result = TestUtils.waitForCondition(() ->
         TestUtils.getRuntime().getObjectStore()
-            .getRaw(ImmutableList.of(helloId.getId()), 0).get(0) == null, 50);
+            .wait(ImmutableList.of(helloId.getId()), 1, 0).get(0) == false, 50);
     Assert.assertTrue(result);
   }
 
diff --git a/python/ray/_raylet.pyx b/python/ray/_raylet.pyx
index abc7d1bbd..8e9f6541d 100644
--- a/python/ray/_raylet.pyx
+++ b/python/ray/_raylet.pyx
@@ -452,7 +452,7 @@ cdef deserialize_args(
                     c_args[i].get().GetMetadata()).to_pybytes()
                     == RAW_BUFFER_METADATA):
                 data = Buffer.make(c_args[i].get().GetData())
-                args.append(data)
+                args.append(data.to_pybytes())
             elif (c_args[i].get().HasMetadata() and Buffer.make(
                     c_args[i].get().GetMetadata()).to_pybytes()
                     == PICKLE_BUFFER_METADATA):
diff --git a/python/ray/scripts/scripts.py b/python/ray/scripts/scripts.py
index e2ef2a167..b46d9ca72 100644
--- a/python/ray/scripts/scripts.py
+++ b/python/ray/scripts/scripts.py
@@ -470,7 +470,7 @@ def stop(force, verbose):
         debug_operator = "| tee /dev/stderr" if verbose else ""
 
         command = (
-            "kill -s {} $(ps ax -o {} | grep {} | grep -v grep {} | grep ray |"
+            "kill -s {} $(ps ax -o {} | grep {} | grep -v grep {} |"
             "awk '{{ print $1 }}') 2> /dev/null".format(
                 # ^^ This is how you escape braces in python format string.
                 "KILL" if force else "TERM",
diff --git a/python/ray/services.py b/python/ray/services.py
index d3852186f..7e5577545 100644
--- a/python/ray/services.py
+++ b/python/ray/services.py
@@ -1184,6 +1184,7 @@ def start_raylet(redis_address,
         java_worker_command = build_java_worker_command(
             java_worker_options,
             redis_address,
+            node_manager_port,
             plasma_store_name,
             raylet_name,
             redis_password,
@@ -1251,6 +1252,7 @@ def start_raylet(redis_address,
 def build_java_worker_command(
         java_worker_options,
         redis_address,
+        node_manager_port,
         plasma_store_name,
         raylet_name,
         redis_password,
@@ -1275,6 +1277,7 @@ def build_java_worker_command(
 
     if redis_address is not None:
         command += "-Dray.redis.address={} ".format(redis_address)
+    command += "-Dray.raylet.node-manager-port={} ".format(node_manager_port)
 
     if plasma_store_name is not None:
         command += (
diff --git a/python/ray/signature.py b/python/ray/signature.py
index 2e274d457..daaacf0b1 100644
--- a/python/ray/signature.py
+++ b/python/ray/signature.py
@@ -37,7 +37,9 @@ Attributes:
         by 'functools.partial'.
 """
 
-DUMMY_TYPE = "__RAY_DUMMY__"
+# This dummy type is also defined in ArgumentsBuilder.java. Please keep it
+# synced.
+DUMMY_TYPE = b"__RAY_DUMMY__"
 
 
 def get_signature(func):
diff --git a/src/ray/common/task/task_spec.cc b/src/ray/common/task/task_spec.cc
index 5d96dae98..3506d42df 100644
--- a/src/ray/common/task/task_spec.cc
+++ b/src/ray/common/task/task_spec.cc
@@ -5,6 +5,7 @@
 
 namespace ray {
 
+absl::Mutex TaskSpecification::mutex_;
 std::unordered_map<SchedulingClassDescriptor, SchedulingClass>
     TaskSpecification::sched_cls_to_id_;
 std::unordered_map<SchedulingClass, SchedulingClassDescriptor>
@@ -13,6 +14,7 @@ int TaskSpecification::next_sched_id_;
 
 SchedulingClassDescriptor &TaskSpecification::GetSchedulingClassDescriptor(
     SchedulingClass id) {
+  absl::MutexLock lock(&mutex_);
   auto it = sched_id_to_cls_.find(id);
   RAY_CHECK(it != sched_id_to_cls_.end()) << "invalid id: " << id;
   return it->second;
@@ -30,6 +32,7 @@ void TaskSpecification::ComputeResources() {
 
   // Map the scheduling class descriptor to an integer for performance.
   auto sched_cls = std::make_pair(GetRequiredResources(), FunctionDescriptor());
+  absl::MutexLock lock(&mutex_);
   auto it = sched_cls_to_id_.find(sched_cls);
   if (it == sched_cls_to_id_.end()) {
     sched_cls_id_ = ++next_sched_id_;
diff --git a/src/ray/common/task/task_spec.h b/src/ray/common/task/task_spec.h
index 0c14912d0..2c41d6fee 100644
--- a/src/ray/common/task/task_spec.h
+++ b/src/ray/common/task/task_spec.h
@@ -6,6 +6,7 @@
 #include <unordered_map>
 #include <vector>
 
+#include "absl/synchronization/mutex.h"
 #include "ray/common/grpc_util.h"
 #include "ray/common/id.h"
 #include "ray/common/task/scheduling_resources.h"
@@ -180,10 +181,15 @@ class TaskSpecification : public MessageWrapper<rpc::TaskSpec> {
   /// Cached scheduling class of this task.
   SchedulingClass sched_cls_id_;
 
+  /// Below static fields could be mutated in `ComputeResources` concurrently due to
+  /// multi-threading, we need a mutex to protect it.
+  static absl::Mutex mutex_;
   /// Keep global static id mappings for SchedulingClass for performance.
-  static std::unordered_map<SchedulingClassDescriptor, SchedulingClass> sched_cls_to_id_;
-  static std::unordered_map<SchedulingClass, SchedulingClassDescriptor> sched_id_to_cls_;
-  static int next_sched_id_;
+  static std::unordered_map<SchedulingClassDescriptor, SchedulingClass> sched_cls_to_id_
+      GUARDED_BY(mutex_);
+  static std::unordered_map<SchedulingClass, SchedulingClassDescriptor> sched_id_to_cls_
+      GUARDED_BY(mutex_);
+  static int next_sched_id_ GUARDED_BY(mutex_);
 };
 
 }  // namespace ray
diff --git a/src/ray/core_worker/core_worker.cc b/src/ray/core_worker/core_worker.cc
index ce9851546..c17d569a2 100644
--- a/src/ray/core_worker/core_worker.cc
+++ b/src/ray/core_worker/core_worker.cc
@@ -260,6 +260,7 @@ void CoreWorker::SetCurrentTaskId(const TaskID &task_id) {
   main_thread_task_id_ = task_id;
   // Clear all actor handles at the end of each non-actor task.
   if (actor_id_.IsNil() && task_id.IsNil()) {
+    absl::MutexLock lock(&actor_handles_mutex_);
     for (const auto &handle : actor_handles_) {
       RAY_CHECK_OK(gcs_client_->Actors().AsyncUnsubscribe(handle.first, nullptr));
     }
@@ -722,13 +723,16 @@ Status CoreWorker::SerializeActorHandle(const ActorID &actor_id,
 }
 
 bool CoreWorker::AddActorHandle(std::unique_ptr<ActorHandle> actor_handle) {
+  absl::MutexLock lock(&actor_handles_mutex_);
   const auto &actor_id = actor_handle->GetActorID();
+
   auto inserted = actor_handles_.emplace(actor_id, std::move(actor_handle)).second;
   if (inserted) {
     // Register a callback to handle actor notifications.
     auto actor_notification_callback = [this](const ActorID &actor_id,
                                               const gcs::ActorTableData &actor_data) {
       if (actor_data.state() == gcs::ActorTableData::RECONSTRUCTING) {
+        absl::MutexLock lock(&actor_handles_mutex_);
         auto it = actor_handles_.find(actor_id);
         RAY_CHECK(it != actor_handles_.end());
         if (it->second->IsDirectCallActor()) {
@@ -761,6 +765,7 @@ bool CoreWorker::AddActorHandle(std::unique_ptr<ActorHandle> actor_handle) {
 
 Status CoreWorker::GetActorHandle(const ActorID &actor_id,
                                   ActorHandle **actor_handle) const {
+  absl::MutexLock lock(&actor_handles_mutex_);
   auto it = actor_handles_.find(actor_id);
   if (it == actor_handles_.end()) {
     return Status::Invalid("Handle for actor does not exist");
diff --git a/src/ray/core_worker/core_worker.h b/src/ray/core_worker/core_worker.h
index c9e03967a..16c024fe1 100644
--- a/src/ray/core_worker/core_worker.h
+++ b/src/ray/core_worker/core_worker.h
@@ -362,6 +362,13 @@ class CoreWorker {
                                const std::vector<std::shared_ptr<Buffer>> &metadatas,
                                std::vector<std::shared_ptr<RayObject>> *return_objects);
 
+  /// Get a handle to an actor.
+  ///
+  /// \param[in] actor_id The actor handle to get.
+  /// \param[out] actor_handle A handle to the requested actor.
+  /// \return Status::Invalid if we don't have this actor handle.
+  Status GetActorHandle(const ActorID &actor_id, ActorHandle **actor_handle) const;
+
   ///
   /// The following methods are handlers for the core worker's gRPC server, which follow
   /// a macro-generated call convention. These are executed on the io_service_ and
@@ -428,14 +435,6 @@ class CoreWorker {
   /// to the same actor.
   bool AddActorHandle(std::unique_ptr<ActorHandle> actor_handle);
 
-  /// Get a handle to an actor. This asserts that the worker actually has this
-  /// handle.
-  ///
-  /// \param[in] actor_id The actor handle to get.
-  /// \param[out] actor_handle A handle to the requested actor.
-  /// \return Status::Invalid if we don't have this actor handle.
-  Status GetActorHandle(const ActorID &actor_id, ActorHandle **actor_handle) const;
-
   ///
   /// Private methods related to task execution. Should not be used by driver processes.
   ///
@@ -559,8 +558,13 @@ class CoreWorker {
   // Interface to submit non-actor tasks directly to leased workers.
   std::unique_ptr<CoreWorkerDirectTaskSubmitter> direct_task_submitter_;
 
+  /// The `actor_handles_` field could be mutated concurrently due to multi-threading, we
+  /// need a mutex to protect it.
+  mutable absl::Mutex actor_handles_mutex_;
+
   /// Map from actor ID to a handle to that actor.
-  absl::flat_hash_map<ActorID, std::unique_ptr<ActorHandle>> actor_handles_;
+  absl::flat_hash_map<ActorID, std::unique_ptr<ActorHandle>> actor_handles_
+      GUARDED_BY(actor_handles_mutex_);
 
   /// Resolve local and remote dependencies for actor creation.
   std::unique_ptr<LocalDependencyResolver> resolver_;
diff --git a/src/ray/core_worker/lib/java/jni_utils.h b/src/ray/core_worker/lib/java/jni_utils.h
index 365b885c0..e5de78931 100644
--- a/src/ray/core_worker/lib/java/jni_utils.h
+++ b/src/ray/core_worker/lib/java/jni_utils.h
@@ -152,6 +152,8 @@ class JavaByteArrayBuffer : public ray::Buffer {
 
   bool OwnsData() const override { return true; }
 
+  bool IsPlasmaBuffer() const { return false; }
+
   ~JavaByteArrayBuffer() {
     env_->ReleaseByteArrayElements(java_byte_array_, native_bytes_, JNI_ABORT);
   }
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.cc b/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.cc
index e19cc9e5d..40ee3351d 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.cc
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.cc
@@ -23,19 +23,15 @@ inline ray::gcs::GcsClientOptions ToGcsClientOptions(JNIEnv *env,
 extern "C" {
 #endif
 
-/*
- * Class:     org_ray_runtime_RayNativeRuntime
- * Method:    nativeInitCoreWorker
- * Signature:
- * (ILjava/lang/String;Ljava/lang/String;[BLorg/ray/runtime/gcs/GcsClientOptions;)J
- */
 JNIEXPORT jlong JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeInitCoreWorker(
     JNIEnv *env, jclass, jint workerMode, jstring storeSocket, jstring rayletSocket,
-    jbyteArray jobId, jobject gcsClientOptions) {
+    jstring nodeIpAddress, jint nodeManagerPort, jbyteArray jobId,
+    jobject gcsClientOptions) {
   auto native_store_socket = JavaStringToNativeString(env, storeSocket);
   auto native_raylet_socket = JavaStringToNativeString(env, rayletSocket);
   auto job_id = JavaByteArrayToId<ray::JobID>(env, jobId);
   auto gcs_client_options = ToGcsClientOptions(env, gcsClientOptions);
+  auto node_ip_address = JavaStringToNativeString(env, nodeIpAddress);
 
   auto task_execution_callback =
       [](ray::TaskType task_type, const ray::RayFunction &ray_function,
@@ -74,8 +70,8 @@ JNIEXPORT jlong JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeInitCoreWork
   try {
     auto core_worker = new ray::CoreWorker(
         static_cast<ray::WorkerType>(workerMode), ::Language::JAVA, native_store_socket,
-        native_raylet_socket, job_id, gcs_client_options, /*log_dir=*/"",
-        /*node_ip_address=*/"", task_execution_callback);
+        native_raylet_socket, job_id, gcs_client_options, /*log_dir=*/"", node_ip_address,
+        nodeManagerPort, task_execution_callback);
     return reinterpret_cast<jlong>(core_worker);
   } catch (const std::exception &e) {
     std::ostringstream oss;
@@ -85,11 +81,6 @@ JNIEXPORT jlong JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeInitCoreWork
   }
 }
 
-/*
- * Class:     org_ray_runtime_RayNativeRuntime
- * Method:    nativeRunTaskExecutor
- * Signature: (JLorg/ray/runtime/task/TaskExecutor;)V
- */
 JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeRunTaskExecutor(
     JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer, jobject javaTaskExecutor) {
   local_env = env;
@@ -100,11 +91,6 @@ JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeRunTaskExecut
   local_java_task_executor = nullptr;
 }
 
-/*
- * Class:     org_ray_runtime_RayNativeRuntime
- * Method:    nativeDestroyCoreWorker
- * Signature: (J)V
- */
 JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeDestroyCoreWorker(
     JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer) {
   auto core_worker = reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer);
@@ -112,11 +98,6 @@ JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeDestroyCoreWo
   delete core_worker;
 }
 
-/*
- * Class:     org_ray_runtime_RayNativeRuntime
- * Method:    nativeSetup
- * Signature: (Ljava/lang/String;)V
- */
 JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeSetup(JNIEnv *env,
                                                                          jclass,
                                                                          jstring logDir) {
@@ -125,21 +106,11 @@ JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeSetup(JNIEnv
   // TODO (kfstorm): If we add InstallFailureSignalHandler here, Java test may crash.
 }
 
-/*
- * Class:     org_ray_runtime_RayNativeRuntime
- * Method:    nativeShutdownHook
- * Signature: ()V
- */
 JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeShutdownHook(JNIEnv *,
                                                                                 jclass) {
   ray::RayLog::ShutDownRayLog();
 }
 
-/*
- * Class:     org_ray_runtime_RayNativeRuntime
- * Method:    nativeSetResource
- * Signature: (JLjava/lang/String;D[B)V
- */
 JNIEXPORT void JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeSetResource(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jstring resourceName,
     jdouble capacity, jbyteArray nodeId) {
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.h b/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.h
index 480564640..48bc81f04 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.h
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_RayNativeRuntime.h
@@ -11,10 +11,10 @@ extern "C" {
  * Class:     org_ray_runtime_RayNativeRuntime
  * Method:    nativeInitCoreWorker
  * Signature:
- * (ILjava/lang/String;Ljava/lang/String;[BLorg/ray/runtime/gcs/GcsClientOptions;)J
+ * (ILjava/lang/String;Ljava/lang/String;Ljava/lang/String;I[BLorg/ray/runtime/gcs/GcsClientOptions;)J
  */
 JNIEXPORT jlong JNICALL Java_org_ray_runtime_RayNativeRuntime_nativeInitCoreWorker(
-    JNIEnv *, jclass, jint, jstring, jstring, jbyteArray, jobject);
+    JNIEnv *, jclass, jint, jstring, jstring, jstring, jint, jbyteArray, jobject);
 
 /*
  * Class:     org_ray_runtime_RayNativeRuntime
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.cc b/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.cc
index 41715f3b6..e4379f98e 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.cc
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.cc
@@ -2,119 +2,71 @@
 #include <jni.h>
 #include "ray/common/id.h"
 #include "ray/core_worker/common.h"
+#include "ray/core_worker/core_worker.h"
 #include "ray/core_worker/lib/java/jni_utils.h"
-#include "ray/core_worker/task_interface.h"
 
-inline ray::ActorHandle &GetActorHandle(jlong nativeActorHandle) {
-  return *(reinterpret_cast<ray::ActorHandle *>(nativeActorHandle));
+inline ray::CoreWorker &GetCoreWorker(jlong nativeCoreWorkerPointer) {
+  return *reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer);
 }
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeFork
- * Signature: (J)J
- */
-JNIEXPORT jlong JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeFork(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  return reinterpret_cast<jlong>(GetActorHandle(nativeActorHandle).Fork().release());
-}
-
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeGetActorId
- * Signature: (J)[B
- */
-JNIEXPORT jbyteArray JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeGetActorId(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  return IdToJavaByteArray<ray::ActorID>(env,
-                                         GetActorHandle(nativeActorHandle).GetActorID());
-}
-
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeGetActorHandleId
- * Signature: (J)[B
- */
-JNIEXPORT jbyteArray JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeGetActorHandleId(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  return IdToJavaByteArray<ray::ActorHandleID>(
-      env, GetActorHandle(nativeActorHandle).GetActorHandleID());
-}
-
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeGetLanguage
- * Signature: (J)I
- */
 JNIEXPORT jint JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeGetLanguage(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  return (jint)GetActorHandle(nativeActorHandle).ActorLanguage();
+    JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer, jbyteArray actorId) {
+  auto actor_id = JavaByteArrayToId<ray::ActorID>(env, actorId);
+  ray::ActorHandle *native_actor_handle = nullptr;
+  auto status = GetCoreWorker(nativeCoreWorkerPointer)
+                    .GetActorHandle(actor_id, &native_actor_handle);
+  THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, (jint)0);
+  return (jint)native_actor_handle->ActorLanguage();
 }
 
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeIsDirectCallActor
- * Signature: (J)Z
- */
 JNIEXPORT jboolean JNICALL
 Java_org_ray_runtime_actor_NativeRayActor_nativeIsDirectCallActor(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  return GetActorHandle(nativeActorHandle).IsDirectCallActor();
+    JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer, jbyteArray actorId) {
+  auto actor_id = JavaByteArrayToId<ray::ActorID>(env, actorId);
+  ray::ActorHandle *native_actor_handle = nullptr;
+  auto status = GetCoreWorker(nativeCoreWorkerPointer)
+                    .GetActorHandle(actor_id, &native_actor_handle);
+  THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, false);
+  return native_actor_handle->IsDirectCallActor();
 }
 
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeGetActorCreationTaskFunctionDescriptor
- * Signature: (J)Ljava/util/List;
- */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_actor_NativeRayActor_nativeGetActorCreationTaskFunctionDescriptor(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  return NativeStringVectorToJavaStringList(
-      env, GetActorHandle(nativeActorHandle).ActorCreationTaskFunctionDescriptor());
+    JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer, jbyteArray actorId) {
+  auto actor_id = JavaByteArrayToId<ray::ActorID>(env, actorId);
+  ray::ActorHandle *native_actor_handle = nullptr;
+  auto status = GetCoreWorker(nativeCoreWorkerPointer)
+                    .GetActorHandle(actor_id, &native_actor_handle);
+  THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
+  auto function_descriptor = native_actor_handle->ActorCreationTaskFunctionDescriptor();
+  return NativeStringVectorToJavaStringList(env, function_descriptor);
 }
 
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeSerialize
- * Signature: (J)[B
- */
 JNIEXPORT jbyteArray JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeSerialize(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
+    JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer, jbyteArray actorId) {
+  auto actor_id = JavaByteArrayToId<ray::ActorID>(env, actorId);
   std::string output;
-  GetActorHandle(nativeActorHandle).Serialize(&output);
+  ray::Status status =
+      GetCoreWorker(nativeCoreWorkerPointer).SerializeActorHandle(actor_id, &output);
   jbyteArray bytes = env->NewByteArray(output.size());
   env->SetByteArrayRegion(bytes, 0, output.size(),
                           reinterpret_cast<const jbyte *>(output.c_str()));
   return bytes;
 }
 
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeDeserialize
- * Signature: ([B)J
- */
-JNIEXPORT jlong JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeDeserialize(
-    JNIEnv *env, jclass o, jbyteArray data) {
+JNIEXPORT jbyteArray JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeDeserialize(
+    JNIEnv *env, jclass o, jlong nativeCoreWorkerPointer, jbyteArray data) {
   auto buffer = JavaByteArrayToNativeBuffer(env, data);
   RAY_CHECK(buffer->Size() > 0);
   auto binary = std::string(reinterpret_cast<char *>(buffer->Data()), buffer->Size());
-  return reinterpret_cast<jlong>(new ray::ActorHandle(binary, TaskID::Nil()));
-}
+  auto actor_id =
+      GetCoreWorker(nativeCoreWorkerPointer).DeserializeAndRegisterActorHandle(binary);
 
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeFree
- * Signature: (J)V
- */
-JNIEXPORT void JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeFree(
-    JNIEnv *env, jclass o, jlong nativeActorHandle) {
-  delete &GetActorHandle(nativeActorHandle);
+  return IdToJavaByteArray<ray::ActorID>(env, actor_id);
 }
 
 #ifdef __cplusplus
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.h b/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.h
index 245064fcf..8f75e3a82 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.h
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_actor_NativeRayActor.h
@@ -7,80 +7,47 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeFork
- * Signature: (J)J
- */
-JNIEXPORT jlong JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeFork(JNIEnv *,
-                                                                             jclass,
-                                                                             jlong);
-
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeGetActorId
- * Signature: (J)[B
- */
-JNIEXPORT jbyteArray JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeGetActorId(JNIEnv *, jclass, jlong);
-
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeGetActorHandleId
- * Signature: (J)[B
- */
-JNIEXPORT jbyteArray JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeGetActorHandleId(JNIEnv *, jclass, jlong);
-
 /*
  * Class:     org_ray_runtime_actor_NativeRayActor
  * Method:    nativeGetLanguage
- * Signature: (J)I
+ * Signature: (J[B)I
  */
-JNIEXPORT jint JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeGetLanguage(JNIEnv *, jclass, jlong);
+JNIEXPORT jint JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeGetLanguage(
+    JNIEnv *, jclass, jlong, jbyteArray);
 
 /*
  * Class:     org_ray_runtime_actor_NativeRayActor
  * Method:    nativeIsDirectCallActor
- * Signature: (J)Z
+ * Signature: (J[B)Z
  */
 JNIEXPORT jboolean JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeIsDirectCallActor(JNIEnv *, jclass, jlong);
+Java_org_ray_runtime_actor_NativeRayActor_nativeIsDirectCallActor(JNIEnv *, jclass, jlong,
+                                                                  jbyteArray);
 
 /*
  * Class:     org_ray_runtime_actor_NativeRayActor
  * Method:    nativeGetActorCreationTaskFunctionDescriptor
- * Signature: (J)Ljava/util/List;
+ * Signature: (J[B)Ljava/util/List;
  */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_actor_NativeRayActor_nativeGetActorCreationTaskFunctionDescriptor(
-    JNIEnv *, jclass, jlong);
+    JNIEnv *, jclass, jlong, jbyteArray);
 
 /*
  * Class:     org_ray_runtime_actor_NativeRayActor
  * Method:    nativeSerialize
- * Signature: (J)[B
+ * Signature: (J[B)[B
  */
-JNIEXPORT jbyteArray JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeSerialize(JNIEnv *, jclass, jlong);
+JNIEXPORT jbyteArray JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeSerialize(
+    JNIEnv *, jclass, jlong, jbyteArray);
 
 /*
  * Class:     org_ray_runtime_actor_NativeRayActor
  * Method:    nativeDeserialize
- * Signature: ([B)J
+ * Signature: (J[B)[B
  */
-JNIEXPORT jlong JNICALL
-Java_org_ray_runtime_actor_NativeRayActor_nativeDeserialize(JNIEnv *, jclass, jbyteArray);
-
-/*
- * Class:     org_ray_runtime_actor_NativeRayActor
- * Method:    nativeFree
- * Signature: (J)V
- */
-JNIEXPORT void JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeFree(JNIEnv *,
-                                                                            jclass,
-                                                                            jlong);
+JNIEXPORT jbyteArray JNICALL Java_org_ray_runtime_actor_NativeRayActor_nativeDeserialize(
+    JNIEnv *, jclass, jlong, jbyteArray);
 
 #ifdef __cplusplus
 }
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_context_NativeWorkerContext.cc b/src/ray/core_worker/lib/java/org_ray_runtime_context_NativeWorkerContext.cc
index b7e791044..49e3e3118 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_context_NativeWorkerContext.cc
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_context_NativeWorkerContext.cc
@@ -13,11 +13,6 @@ inline ray::WorkerContext &GetWorkerContextFromPointer(jlong nativeCoreWorkerPoi
 extern "C" {
 #endif
 
-/*
- * Class:     org_ray_runtime_context_NativeWorkerContext
- * Method:    nativeGetCurrentTaskType
- * Signature: (J)I
- */
 JNIEXPORT jint JNICALL
 Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentTaskType(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer) {
@@ -26,11 +21,6 @@ Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentTaskType(
   return static_cast<int>(task_spec->GetMessage().type());
 }
 
-/*
- * Class:     org_ray_runtime_context_NativeWorkerContext
- * Method:    nativeGetCurrentTaskId
- * Signature: (J)Ljava/nio/ByteBuffer;
- */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentTaskId(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer) {
@@ -39,11 +29,6 @@ Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentTaskId(
   return IdToJavaByteBuffer<ray::TaskID>(env, task_id);
 }
 
-/*
- * Class:     org_ray_runtime_context_NativeWorkerContext
- * Method:    nativeGetCurrentJobId
- * Signature: (J)Ljava/nio/ByteBuffer;
- */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentJobId(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer) {
@@ -52,11 +37,6 @@ Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentJobId(
   return IdToJavaByteBuffer<ray::JobID>(env, job_id);
 }
 
-/*
- * Class:     org_ray_runtime_context_NativeWorkerContext
- * Method:    nativeGetCurrentWorkerId
- * Signature: (J)Ljava/nio/ByteBuffer;
- */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentWorkerId(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer) {
@@ -65,11 +45,6 @@ Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentWorkerId(
   return IdToJavaByteBuffer<ray::WorkerID>(env, worker_id);
 }
 
-/*
- * Class:     org_ray_runtime_context_NativeWorkerContext
- * Method:    nativeGetCurrentActorId
- * Signature: (J)Ljava/nio/ByteBuffer;
- */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_context_NativeWorkerContext_nativeGetCurrentActorId(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer) {
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_object_NativeObjectStore.cc b/src/ray/core_worker/lib/java/org_ray_runtime_object_NativeObjectStore.cc
index c6b256f95..9bcde92ab 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_object_NativeObjectStore.cc
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_object_NativeObjectStore.cc
@@ -5,20 +5,10 @@
 #include "ray/core_worker/core_worker.h"
 #include "ray/core_worker/lib/java/jni_utils.h"
 
-inline ray::CoreWorkerObjectInterface &GetObjectInterfaceFromPointer(
-    jlong nativeCoreWorkerPointer) {
-  return reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)->Objects();
-}
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/*
- * Class:     org_ray_runtime_object_NativeObjectStore
- * Method:    nativePut
- * Signature: (JLorg/ray/runtime/object/NativeRayObject;)[B
- */
 JNIEXPORT jbyteArray JNICALL
 Java_org_ray_runtime_object_NativeObjectStore_nativePut__JLorg_ray_runtime_object_NativeRayObject_2(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jobject obj) {
@@ -26,16 +16,11 @@ Java_org_ray_runtime_object_NativeObjectStore_nativePut__JLorg_ray_runtime_objec
   RAY_CHECK(ray_object != nullptr);
   ray::ObjectID object_id;
   auto status = reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)
-                    .Put(*ray_object, &object_id);
+                    ->Put(*ray_object, &object_id);
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
   return IdToJavaByteArray<ray::ObjectID>(env, object_id);
 }
 
-/*
- * Class:     org_ray_runtime_object_NativeObjectStore
- * Method:    nativePut
- * Signature: (J[BLorg/ray/runtime/object/NativeRayObject;)V
- */
 JNIEXPORT void JNICALL
 Java_org_ray_runtime_object_NativeObjectStore_nativePut__J_3BLorg_ray_runtime_object_NativeRayObject_2(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jbyteArray objectId,
@@ -44,15 +29,10 @@ Java_org_ray_runtime_object_NativeObjectStore_nativePut__J_3BLorg_ray_runtime_ob
   auto ray_object = JavaNativeRayObjectToNativeRayObject(env, obj);
   RAY_CHECK(ray_object != nullptr);
   auto status = reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)
-                    .Put(*ray_object, object_id);
+                    ->Put(*ray_object, object_id);
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, (void)0);
 }
 
-/*
- * Class:     org_ray_runtime_object_NativeObjectStore
- * Method:    nativeGet
- * Signature: (JLjava/util/List;J)Ljava/util/List;
- */
 JNIEXPORT jobject JNICALL Java_org_ray_runtime_object_NativeObjectStore_nativeGet(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jobject ids, jlong timeoutMs) {
   std::vector<ray::ObjectID> object_ids;
@@ -62,17 +42,12 @@ JNIEXPORT jobject JNICALL Java_org_ray_runtime_object_NativeObjectStore_nativeGe
       });
   std::vector<std::shared_ptr<ray::RayObject>> results;
   auto status = reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)
-                    .Get(object_ids, (int64_t)timeoutMs, &results);
+                    ->Get(object_ids, (int64_t)timeoutMs, &results);
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
   return NativeVectorToJavaList<std::shared_ptr<ray::RayObject>>(
       env, results, NativeRayObjectToJavaNativeRayObject);
 }
 
-/*
- * Class:     org_ray_runtime_object_NativeObjectStore
- * Method:    nativeWait
- * Signature: (JLjava/util/List;IJ)Ljava/util/List;
- */
 JNIEXPORT jobject JNICALL Java_org_ray_runtime_object_NativeObjectStore_nativeWait(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jobject objectIds,
     jint numObjects, jlong timeoutMs) {
@@ -83,18 +58,13 @@ JNIEXPORT jobject JNICALL Java_org_ray_runtime_object_NativeObjectStore_nativeWa
       });
   std::vector<bool> results;
   auto status = reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)
-                    .Wait(object_ids, (int)numObjects, (int64_t)timeoutMs, &results);
+                    ->Wait(object_ids, (int)numObjects, (int64_t)timeoutMs, &results);
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
   return NativeVectorToJavaList<bool>(env, results, [](JNIEnv *env, const bool &item) {
     return env->NewObject(java_boolean_class, java_boolean_init, (jboolean)item);
   });
 }
 
-/*
- * Class:     org_ray_runtime_object_NativeObjectStore
- * Method:    nativeDelete
- * Signature: (JLjava/util/List;ZZ)V
- */
 JNIEXPORT void JNICALL Java_org_ray_runtime_object_NativeObjectStore_nativeDelete(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jobject objectIds,
     jboolean localOnly, jboolean deleteCreatingTasks) {
@@ -104,7 +74,7 @@ JNIEXPORT void JNICALL Java_org_ray_runtime_object_NativeObjectStore_nativeDelet
         return JavaByteArrayToId<ray::ObjectID>(env, static_cast<jbyteArray>(id));
       });
   auto status = reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)
-                    .Delete(object_ids, (bool)localOnly, (bool)deleteCreatingTasks);
+                    ->Delete(object_ids, (bool)localOnly, (bool)deleteCreatingTasks);
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, (void)0);
 }
 
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskExecutor.cc b/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskExecutor.cc
index 8658c2f8a..86229cfac 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskExecutor.cc
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskExecutor.cc
@@ -12,11 +12,6 @@ extern "C" {
 
 using ray::ClientID;
 
-/*
- * Class:     org_ray_runtime_task_NativeTaskExecutor
- * Method:    nativePrepareCheckpoint
- * Signature: (J)[B
- */
 JNIEXPORT jbyteArray JNICALL
 Java_org_ray_runtime_task_NativeTaskExecutor_nativePrepareCheckpoint(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer) {
@@ -25,8 +20,8 @@ Java_org_ray_runtime_task_NativeTaskExecutor_nativePrepareCheckpoint(
   const auto &task_spec = core_worker.GetWorkerContext().GetCurrentTask();
   RAY_CHECK(task_spec->IsActorTask());
   ActorCheckpointID checkpoint_id;
-  auto status = core_worker.GetRayletClient().PrepareActorCheckpoint(
-      actor_id, checkpoint_id);
+  auto status =
+      core_worker.GetRayletClient().PrepareActorCheckpoint(actor_id, checkpoint_id);
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
   jbyteArray result = env->NewByteArray(checkpoint_id.Size());
   env->SetByteArrayRegion(result, 0, checkpoint_id.Size(),
@@ -34,11 +29,6 @@ Java_org_ray_runtime_task_NativeTaskExecutor_nativePrepareCheckpoint(
   return result;
 }
 
-/*
- * Class:     org_ray_runtime_task_NativeTaskExecutor
- * Method:    nativeNotifyActorResumedFromCheckpoint
- * Signature: (J[B)V
- */
 JNIEXPORT void JNICALL
 Java_org_ray_runtime_task_NativeTaskExecutor_nativeNotifyActorResumedFromCheckpoint(
     JNIEnv *env, jclass, jlong nativeCoreWorkerPointer, jbyteArray checkpointId) {
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.cc b/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.cc
index 129a49aa9..632f8db96 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.cc
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.cc
@@ -4,11 +4,9 @@
 #include "ray/core_worker/common.h"
 #include "ray/core_worker/core_worker.h"
 #include "ray/core_worker/lib/java/jni_utils.h"
-#include "ray/core_worker/task_interface.h"
 
-inline ray::CoreWorkerTaskInterface &GetTaskInterfaceFromPointer(
-    jlong nativeCoreWorkerPointer) {
-  return reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer)->Tasks();
+inline ray::CoreWorker &GetCoreWorker(jlong nativeCoreWorkerPointer) {
+  return *reinterpret_cast<ray::CoreWorker *>(nativeCoreWorkerPointer);
 }
 
 inline ray::RayFunction ToRayFunction(JNIEnv *env, jobject functionDescriptor) {
@@ -70,7 +68,7 @@ inline ray::TaskOptions ToTaskOptions(JNIEnv *env, jint numReturns, jobject call
     resources = ToResources(env, java_resources);
   }
 
-  ray::TaskOptions task_options{numReturns, resources};
+  ray::TaskOptions task_options{numReturns, /*is_direct_call=*/false, resources};
   return task_options;
 }
 
@@ -100,22 +98,22 @@ inline ray::ActorCreationOptions ToActorCreationOptions(JNIEnv *env,
                                    java_actor_creation_options_default_use_direct_call);
   }
 
-  ray::ActorCreationOptions action_creation_options{
-      static_cast<uint64_t>(max_reconstructions), use_direct_call, resources, resources,
-      dynamic_worker_options};
-  return action_creation_options;
+  ray::ActorCreationOptions actor_creation_options{
+      static_cast<uint64_t>(max_reconstructions),
+      use_direct_call,
+      /*max_concurrency=*/1,
+      resources,
+      resources,
+      dynamic_worker_options,
+      /*is_detached=*/false,
+      /*is_asyncio=*/false};
+  return actor_creation_options;
 }
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/*
- * Class:     org_ray_runtime_task_NativeTaskSubmitter
- * Method:    nativeSubmitTask
- * Signature:
- * (JLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;ILorg/ray/api/options/CallOptions;)Ljava/util/List;
- */
 JNIEXPORT jobject JNICALL Java_org_ray_runtime_task_NativeTaskSubmitter_nativeSubmitTask(
     JNIEnv *env, jclass p, jlong nativeCoreWorkerPointer, jobject functionDescriptor,
     jobject args, jint numReturns, jobject callOptions) {
@@ -124,55 +122,44 @@ JNIEXPORT jobject JNICALL Java_org_ray_runtime_task_NativeTaskSubmitter_nativeSu
   auto task_options = ToTaskOptions(env, numReturns, callOptions);
 
   std::vector<ObjectID> return_ids;
-  auto status = GetTaskInterfaceFromPointer(nativeCoreWorkerPointer)
-                    .SubmitTask(ray_function, task_args, task_options, &return_ids);
+  auto status = GetCoreWorker(nativeCoreWorkerPointer)
+                    .SubmitTask(ray_function, task_args, task_options, &return_ids, /*max_retries=*/1);
 
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
 
   return NativeIdVectorToJavaByteArrayList(env, return_ids);
 }
 
-/*
- * Class:     org_ray_runtime_task_NativeTaskSubmitter
- * Method:    nativeCreateActor
- * Signature:
- * (JLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;Lorg/ray/api/options/ActorCreationOptions;)J
- */
-JNIEXPORT jlong JNICALL Java_org_ray_runtime_task_NativeTaskSubmitter_nativeCreateActor(
+JNIEXPORT jbyteArray JNICALL
+Java_org_ray_runtime_task_NativeTaskSubmitter_nativeCreateActor(
     JNIEnv *env, jclass p, jlong nativeCoreWorkerPointer, jobject functionDescriptor,
     jobject args, jobject actorCreationOptions) {
   auto ray_function = ToRayFunction(env, functionDescriptor);
   auto task_args = ToTaskArgs(env, args);
   auto actor_creation_options = ToActorCreationOptions(env, actorCreationOptions);
 
-  std::unique_ptr<ray::ActorHandle> actor_handle;
+  ray::ActorID actor_id;
   auto status =
-      GetTaskInterfaceFromPointer(nativeCoreWorkerPointer)
-          .CreateActor(ray_function, task_args, actor_creation_options, &actor_handle);
+      GetCoreWorker(nativeCoreWorkerPointer)
+          .CreateActor(ray_function, task_args, actor_creation_options, &actor_id);
 
-  THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, 0);
-  return reinterpret_cast<jlong>(actor_handle.release());
+  THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
+  return IdToJavaByteArray<ray::ActorID>(env, actor_id);
 }
 
-/*
- * Class:     org_ray_runtime_task_NativeTaskSubmitter
- * Method:    nativeSubmitActorTask
- * Signature:
- * (JJLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;ILorg/ray/api/options/CallOptions;)Ljava/util/List;
- */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_task_NativeTaskSubmitter_nativeSubmitActorTask(
-    JNIEnv *env, jclass p, jlong nativeCoreWorkerPointer, jlong nativeActorHandle,
+    JNIEnv *env, jclass p, jlong nativeCoreWorkerPointer, jbyteArray actorId,
     jobject functionDescriptor, jobject args, jint numReturns, jobject callOptions) {
-  auto &actor_handle = *(reinterpret_cast<ray::ActorHandle *>(nativeActorHandle));
+  auto actor_id = JavaByteArrayToId<ray::ActorID>(env, actorId);
   auto ray_function = ToRayFunction(env, functionDescriptor);
   auto task_args = ToTaskArgs(env, args);
   auto task_options = ToTaskOptions(env, numReturns, callOptions);
 
   std::vector<ObjectID> return_ids;
-  auto status = GetTaskInterfaceFromPointer(nativeCoreWorkerPointer)
-                    .SubmitActorTask(actor_handle, ray_function, task_args, task_options,
-                                     &return_ids);
+  auto status =
+      GetCoreWorker(nativeCoreWorkerPointer)
+          .SubmitActorTask(actor_id, ray_function, task_args, task_options, &return_ids);
 
   THROW_EXCEPTION_AND_RETURN_IF_NOT_OK(env, status, nullptr);
   return NativeIdVectorToJavaByteArrayList(env, return_ids);
diff --git a/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.h b/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.h
index 908b5eee4..22b6337c2 100644
--- a/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.h
+++ b/src/ray/core_worker/lib/java/org_ray_runtime_task_NativeTaskSubmitter.h
@@ -20,22 +20,24 @@ JNIEXPORT jobject JNICALL Java_org_ray_runtime_task_NativeTaskSubmitter_nativeSu
  * Class:     org_ray_runtime_task_NativeTaskSubmitter
  * Method:    nativeCreateActor
  * Signature:
- * (JLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;Lorg/ray/api/options/ActorCreationOptions;)J
+ * (JLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;Lorg/ray/api/options/ActorCreationOptions;)[B
  */
-JNIEXPORT jlong JNICALL Java_org_ray_runtime_task_NativeTaskSubmitter_nativeCreateActor(
-    JNIEnv *, jclass, jlong, jobject, jobject, jobject);
+JNIEXPORT jbyteArray JNICALL
+Java_org_ray_runtime_task_NativeTaskSubmitter_nativeCreateActor(JNIEnv *, jclass, jlong,
+                                                                jobject, jobject,
+                                                                jobject);
 
 /*
  * Class:     org_ray_runtime_task_NativeTaskSubmitter
  * Method:    nativeSubmitActorTask
  * Signature:
- * (JJLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;ILorg/ray/api/options/CallOptions;)Ljava/util/List;
+ * (J[BLorg/ray/runtime/functionmanager/FunctionDescriptor;Ljava/util/List;ILorg/ray/api/options/CallOptions;)Ljava/util/List;
  */
 JNIEXPORT jobject JNICALL
 Java_org_ray_runtime_task_NativeTaskSubmitter_nativeSubmitActorTask(JNIEnv *, jclass,
-                                                                    jlong, jlong, jobject,
-                                                                    jobject, jint,
-                                                                    jobject);
+                                                                    jlong, jbyteArray,
+                                                                    jobject, jobject,
+                                                                    jint, jobject);
 
 #ifdef __cplusplus
 }