tests: refactored actor system Test (Thread.sleep replaced with countDownLatch)

@@ -41,6 +41,7 @@ public class ActorSystemTest {
 
     public static final String ROOT_DISPATCHER = "root-dispatcher";
     private static final int _100K = 100 * 1024;
+    public static final int TIMEOUT_AWAIT_MAX_SEC = 10;
 
     private volatile TbActorSystem actorSystem;
     private volatile ExecutorService submitPool;
@@ -52,7 +53,7 @@ public class ActorSystemTest {
         parallelism = Math.max(2, cores / 2);
         TbActorSystemSettings settings = new TbActorSystemSettings(5, parallelism, 42);
         actorSystem = new DefaultTbActorSystem(settings);
-        submitPool = Executors.newWorkStealingPool(parallelism);
+        submitPool = Executors.newFixedThreadPool(parallelism); //order guaranteed
     }
 
     @After
@@ -122,13 +123,23 @@ public class ActorSystemTest {
         ActorTestCtx testCtx1 = getActorTestCtx(1);
         ActorTestCtx testCtx2 = getActorTestCtx(1);
         TbActorId actorId = new TbEntityActorId(new DeviceId(UUID.randomUUID()));
-        submitPool.submit(() -> actorSystem.createRootActor(ROOT_DISPATCHER, new SlowCreateActor.SlowCreateActorCreator(actorId, testCtx1)));
-        submitPool.submit(() -> actorSystem.createRootActor(ROOT_DISPATCHER, new SlowCreateActor.SlowCreateActorCreator(actorId, testCtx2)));
+        final CountDownLatch initLatch = new CountDownLatch(1);
+        final CountDownLatch actorsReadyLatch = new CountDownLatch(2);
+        submitPool.submit(() -> {
+            actorSystem.createRootActor(ROOT_DISPATCHER, new SlowCreateActor.SlowCreateActorCreator(actorId, testCtx1, initLatch));
+            actorsReadyLatch.countDown();
+        });
+        submitPool.submit(() -> {
+            actorSystem.createRootActor(ROOT_DISPATCHER, new SlowCreateActor.SlowCreateActorCreator(actorId, testCtx2, initLatch));
+            actorsReadyLatch.countDown();
+        });
+
+        initLatch.countDown(); //replacement for Thread.wait(500) in the SlowCreateActorCreator
+        Assert.assertTrue(actorsReadyLatch.await(TIMEOUT_AWAIT_MAX_SEC, TimeUnit.SECONDS));
 
-        Thread.sleep(1000);
         actorSystem.tell(actorId, new IntTbActorMsg(42));
 
-        Assert.assertTrue(testCtx1.getLatch().await(1, TimeUnit.SECONDS));
+        Assert.assertTrue(testCtx1.getLatch().await(TIMEOUT_AWAIT_MAX_SEC, TimeUnit.SECONDS));
         Assert.assertFalse(testCtx2.getLatch().await(1, TimeUnit.SECONDS));
     }
 
@@ -137,13 +148,21 @@ public class ActorSystemTest {
         actorSystem.createDispatcher(ROOT_DISPATCHER, Executors.newWorkStealingPool(parallelism));
         ActorTestCtx testCtx = getActorTestCtx(1);
         TbActorId actorId = new TbEntityActorId(new DeviceId(UUID.randomUUID()));
-        for (int i = 0; i < 1000; i++) {
-            submitPool.submit(() -> actorSystem.createRootActor(ROOT_DISPATCHER, new SlowCreateActor.SlowCreateActorCreator(actorId, testCtx)));
+        final int actorsCount = 1000;
+        final CountDownLatch initLatch = new CountDownLatch(1);
+        final CountDownLatch actorsReadyLatch = new CountDownLatch(actorsCount);
+        for (int i = 0; i < actorsCount; i++) {
+            submitPool.submit(() -> {
+                actorSystem.createRootActor(ROOT_DISPATCHER, new SlowCreateActor.SlowCreateActorCreator(actorId, testCtx, initLatch));
+                actorsReadyLatch.countDown();
+            });
         }
-        Thread.sleep(1000);
+        initLatch.countDown();
+        Assert.assertTrue(actorsReadyLatch.await(TIMEOUT_AWAIT_MAX_SEC, TimeUnit.SECONDS));
+
         actorSystem.tell(actorId, new IntTbActorMsg(42));
 
-        Assert.assertTrue(testCtx.getLatch().await(1, TimeUnit.SECONDS));
+        Assert.assertTrue(testCtx.getLatch().await(TIMEOUT_AWAIT_MAX_SEC, TimeUnit.SECONDS));
         //One for creation and one for message
         Assert.assertEquals(2, testCtx.getInvocationCount().get());
     }

@@ -17,13 +17,18 @@ package org.thingsboard.server.actors;
 
 import lombok.extern.slf4j.Slf4j;
 
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
 @Slf4j
 public class SlowCreateActor extends TestRootActor {
 
-    public SlowCreateActor(TbActorId actorId, ActorTestCtx testCtx) {
+    public static final int TIMEOUT_AWAIT_MAX_MS = 5000;
+
+    public SlowCreateActor(TbActorId actorId, ActorTestCtx testCtx, CountDownLatch initLatch) {
         super(actorId, testCtx);
         try {
-            Thread.sleep(500);
+            initLatch.await(TIMEOUT_AWAIT_MAX_MS, TimeUnit.MILLISECONDS);
         } catch (InterruptedException e) {
             e.printStackTrace();
         }
@@ -34,10 +39,12 @@ public class SlowCreateActor extends TestRootActor {
 
         private final TbActorId actorId;
         private final ActorTestCtx testCtx;
+        private final CountDownLatch initLatch;
 
-        public SlowCreateActorCreator(TbActorId actorId, ActorTestCtx testCtx) {
+        public SlowCreateActorCreator(TbActorId actorId, ActorTestCtx testCtx, CountDownLatch initLatch) {
             this.actorId = actorId;
             this.testCtx = testCtx;
+            this.initLatch = initLatch;
         }
 
         @Override
@@ -47,7 +54,7 @@ public class SlowCreateActor extends TestRootActor {
 
         @Override
         public TbActor createActor() {
-            return new SlowCreateActor(actorId, testCtx);
+            return new SlowCreateActor(actorId, testCtx, initLatch);
         }
     }
 }