[Java] Support concurrent actor calls API. (#7022)

* WIP

Temp change

Attach native thread to jvm

* Fix run mode

* Address comments.

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

@@ -95,8 +95,8 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
         new GcsClientOptions(rayConfig));
     Preconditions.checkState(nativeCoreWorkerPointer != 0);
 
-    taskExecutor = new NativeTaskExecutor(nativeCoreWorkerPointer, this);
     workerContext = new NativeWorkerContext(nativeCoreWorkerPointer);
+    taskExecutor = new NativeTaskExecutor(nativeCoreWorkerPointer, this);
     objectStore = new NativeObjectStore(workerContext, nativeCoreWorkerPointer);
     taskSubmitter = new NativeTaskSubmitter(nativeCoreWorkerPointer);
 
@@ -153,13 +153,17 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
   }
 
   public void run() {
-    nativeRunTaskExecutor(nativeCoreWorkerPointer, taskExecutor);
+    nativeRunTaskExecutor(nativeCoreWorkerPointer);
   }
 
   public long getNativeCoreWorkerPointer() {
     return nativeCoreWorkerPointer;
   }
 
+  public TaskExecutor getTaskExecutor() {
+    return taskExecutor;
+  }
+
   /**
    * Register this worker or driver to GCS.
    */
@@ -189,8 +193,7 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
       String rayletSocket, String nodeIpAddress, int nodeManagerPort, byte[] jobId,
       GcsClientOptions gcsClientOptions);
 
-  private static native void nativeRunTaskExecutor(long nativeCoreWorkerPointer,
-      TaskExecutor taskExecutor);
+  private static native void nativeRunTaskExecutor(long nativeCoreWorkerPointer);
 
   private static native void nativeDestroyCoreWorker(long nativeCoreWorkerPointer);
 

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

@@ -3,11 +3,15 @@ package org.ray.runtime.task;
 import com.google.common.base.Preconditions;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ConcurrentHashMap;
 import org.ray.api.exception.RayTaskException;
 import org.ray.api.id.ActorId;
 import org.ray.api.id.JobId;
 import org.ray.api.id.TaskId;
+import org.ray.api.id.UniqueId;
 import org.ray.runtime.AbstractRayRuntime;
+import org.ray.runtime.config.RayConfig;
+import org.ray.runtime.config.RunMode;
 import org.ray.runtime.functionmanager.JavaFunctionDescriptor;
 import org.ray.runtime.functionmanager.RayFunction;
 import org.ray.runtime.generated.Common.TaskType;
@@ -23,6 +27,10 @@ public abstract class TaskExecutor {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(TaskExecutor.class);
 
+  // A helper map to help we get the corresponding executor for the given worker in JNI.
+  private static ConcurrentHashMap<UniqueId, TaskExecutor> taskExecutors
+      = new ConcurrentHashMap<>();
+
   protected final AbstractRayRuntime runtime;
 
   /**
@@ -37,6 +45,13 @@ public abstract class TaskExecutor {
 
   protected TaskExecutor(AbstractRayRuntime runtime) {
     this.runtime = runtime;
+    if (RayConfig.getInstance().runMode == RunMode.CLUSTER) {
+      taskExecutors.put(runtime.getWorkerContext().getCurrentWorkerId(), this);
+    }
+  }
+
+  public static TaskExecutor get(byte[] workerId) {
+    return taskExecutors.get(new UniqueId(workerId));
   }
 
   protected List<NativeRayObject> execute(List<String> rayFunctionInfo,