code: package io.ray.test;
  
  import io.ray.api.ActorHandle;
  import io.ray.api.ObjectRef;
  import io.ray.api.Ray;
  import io.ray.api.id.ActorId;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import org.testng.Assert;
  import org.testng.annotations.Test;
  
  public class LocalModeTest extends BaseTest {
  
    private static final int NUM_ACTOR_INSTANCE = 10;
  
    private static final int TIMES_TO_CALL_PER_ACTOR = 10;
  
    static class MyActor {
      public MyActor() {}
  
      public long getThreadId() {
        return Thread.currentThread().getId();
      }
    }
  
    @Test(groups = {"local"})
    public void testActorTasksInOneThread() {
      List<ActorHandle<MyActor>> actors = new ArrayList<>();
      Map<ActorId, Long> actorThreadIds = new HashMap<>();
      for (int i = 0; i < NUM_ACTOR_INSTANCE; ++i) {
        ActorHandle<MyActor> actor = Ray.actor(MyActor::new).remote();
        actors.add(actor);
        actorThreadIds.put(actor.getId(), actor.task(MyActor::getThreadId).remote().get());
      }
  
      Map<ActorId, List<ObjectRef<Long>>> allResults = new HashMap<>();
      for (int i = 0; i < NUM_ACTOR_INSTANCE; ++i) {
        final ActorHandle<MyActor> actor = actors.get(i);
        List<ObjectRef<Long>> thisActorResult = new ArrayList<>();
        for (int j = 0; j < TIMES_TO_CALL_PER_ACTOR; ++j) {
          thisActorResult.add(actor.task(MyActor::getThreadId).remote());
        }
        allResults.put(actor.getId(), thisActorResult);
      }
  
      // check result.
      for (int i = 0; i < NUM_ACTOR_INSTANCE; ++i) {
        final ActorHandle<MyActor> actor = actors.get(i);
        final List<ObjectRef<Long>> thisActorResult = allResults.get(actor.getId());
        // assert
        for (ObjectRef<Long> threadId : thisActorResult) {
          Assert.assertEquals(threadId.get(), actorThreadIds.get(actor.getId()));
        }
      }
    }
  }
  