diff --git a/azure-servicebus/src/main/java/com/microsoft/azure/servicebus/primitives/ClientEntity.java b/azure-servicebus/src/main/java/com/microsoft/azure/servicebus/primitives/ClientEntity.java
index 86156dc5..5a938060 100644
--- a/azure-servicebus/src/main/java/com/microsoft/azure/servicebus/primitives/ClientEntity.java
+++ b/azure-servicebus/src/main/java/com/microsoft/azure/servicebus/primitives/ClientEntity.java
@@ -4,6 +4,8 @@
  */
 package com.microsoft.azure.servicebus.primitives;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
@@ -21,6 +23,7 @@ public abstract class ClientEntity
 
 	private boolean isClosing;
 	private boolean isClosed;
+	private List<CompletableFuture<Void>> closeFutures;
 
 	protected ClientEntity(final String clientId)
 	{
@@ -44,8 +47,7 @@ protected boolean getIsClosed()
 	}
 	
 	protected boolean getIsClosingOrClosed()
-	{
-		
+	{		
 		synchronized (this.syncClose)
 		{
 			return this.isClosing || this.isClosed;
@@ -63,27 +65,49 @@ protected final void setClosed()
 
 	public final CompletableFuture<Void> closeAsync()
 	{
-		if(this.getIsClosingOrClosed())
-		{
-			return CompletableFuture.completedFuture(null);
-		}
-		
 		synchronized (this.syncClose)
 		{
-			this.isClosing = true;
+			if(this.isClosed) {
+				return CompletableFuture.completedFuture(null);
+			}else if (this.isClosing) {
+				if(this.closeFutures == null) {
+					this.closeFutures = new ArrayList<>();
+				}
+				
+				CompletableFuture<Void> closeFuture = new CompletableFuture<>();
+				this.closeFutures.add(closeFuture);
+				return closeFuture;
+			}else {
+				this.isClosing = true;
+			}
 		}
-
-		return this.onClose().thenRunAsync(new Runnable()
-		{
-			@Override
-			public void run()
+		
+		return this.onClose().whenCompleteAsync((v, t) -> {
+			if(t == null)
 			{
-				synchronized (ClientEntity.this.syncClose)
-				{
+				synchronized (ClientEntity.this.syncClose) {
 					ClientEntity.this.isClosing = false;
 					ClientEntity.this.isClosed = true;
+					if(this.closeFutures != null) {
+						for(CompletableFuture<Void> future : this.closeFutures) {
+							AsyncUtil.completeFuture(future, null);
+						}
+					}
+				}
+			}
+			else
+			{
+				// onClose failed with some exception. set isClosing to false, so client can call close again.
+				synchronized (ClientEntity.this.syncClose) {
+					ClientEntity.this.isClosing = false;
+					if(this.closeFutures != null) {
+						for(CompletableFuture<Void> future : this.closeFutures) {
+							AsyncUtil.completeFutureExceptionally(future, t);
+						}
+					}
 				}
-			}}, MessagingFactory.INTERNAL_THREAD_POOL);
+			}
+		}, MessagingFactory.INTERNAL_THREAD_POOL);
 	}
 
 	public final void close() throws ServiceBusException
diff --git a/azure-servicebus/src/test/java/com/microsoft/azure/servicebus/primitives/ClientEntityTests.java b/azure-servicebus/src/test/java/com/microsoft/azure/servicebus/primitives/ClientEntityTests.java
new file mode 100644
index 00000000..d344a165
--- /dev/null
+++ b/azure-servicebus/src/test/java/com/microsoft/azure/servicebus/primitives/ClientEntityTests.java
@@ -0,0 +1,199 @@
+package com.microsoft.azure.servicebus.primitives;
+
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.ForkJoinTask;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class ClientEntityTests {
+	
+	@Test
+	public void closeMultipleTimesTest() {
+		int expectedNumberOfCloseFailures = 5;
+		TestClientEntity clientEntity = new TestClientEntity(expectedNumberOfCloseFailures);
+		int actualCloseFailures = 0;
+		for (int i=0; i<expectedNumberOfCloseFailures + 1; i++)
+		{
+			try {
+				clientEntity.close();
+			} catch (Exception e) {
+				actualCloseFailures++;
+			}
+		}
+		
+		Assert.assertTrue("Entity not closed even after retries.", clientEntity.getIsClosed());
+		Assert.assertEquals("Close didn't fail expected number of times", expectedNumberOfCloseFailures, actualCloseFailures);
+	}
+	
+	@Test
+	public void closeAlreadyClosedEntityTest() {
+		TestClientEntity clientEntity = new TestClientEntity(0);
+		for(int i=0; i<5; i++) {
+			try {
+				clientEntity.close();
+			} catch (ServiceBusException e) {
+				Assert.fail("Entity close threw unexpected exception");
+			}
+		}
+		
+		Assert.assertTrue("Entity not closed.", clientEntity.getIsClosed());
+		Assert.assertEquals("OnClose called on already closed entity.", 1, clientEntity.getTotalNumberOfCloseCalls());
+	}
+	
+	@Test
+	public void concurrentEntityCloseTest() throws InterruptedException, ExecutionException {
+		int numConcurrentCalls = 10;
+		Duration sleepInCloseDuration = Duration.ofSeconds(5);
+		TestClientEntity clientEntity = new TestClientEntity(0, sleepInCloseDuration);
+		ArrayList<ForkJoinTask<CompletableFuture<Void>>> tasks = new ArrayList<>();
+		
+		for (int i=0; i<numConcurrentCalls + 1; i++)
+		{
+			tasks.add(ForkJoinPool.commonPool().submit(() -> clientEntity.closeAsync()));
+		}
+		
+		for (ForkJoinTask<CompletableFuture<Void>> task : tasks) {
+			Assert.assertFalse("Entity closed early.", task.get().isDone());
+		}
+		
+		Assert.assertTrue("Entity not closing even after calling close.", clientEntity.getIsClosingOrClosed());
+		Assert.assertFalse("Entity closed without sleeping.", clientEntity.getIsClosed());
+		
+		Thread.sleep(sleepInCloseDuration.toMillis() + 500); // 500 millis buffer
+		
+		for (ForkJoinTask<CompletableFuture<Void>> task : tasks) {
+			Assert.assertTrue("Entity not closed even after delay.", task.get().isDone());
+		}
+		
+		Assert.assertTrue("Entity not closed even after calling close.", clientEntity.getIsClosed());
+		Assert.assertEquals("OnClose called more than expected number of times", 1, clientEntity.getTotalNumberOfCloseCalls());
+	}
+	
+	@Test
+	public void concurrentEntityCloseFailureTest() throws InterruptedException, ExecutionException {
+		int numConcurrentCalls = 10;
+		Duration sleepInCloseDuration = Duration.ofSeconds(5);
+		TestClientEntity clientEntity = new TestClientEntity(1, sleepInCloseDuration, true);
+		ArrayList<ForkJoinTask<CompletableFuture<Void>>> tasks = new ArrayList<>();
+		
+		for (int i=0; i<numConcurrentCalls + 1; i++)
+		{
+			tasks.add(ForkJoinPool.commonPool().submit(() -> clientEntity.closeAsync()));
+		}
+		
+		for (ForkJoinTask<CompletableFuture<Void>> task : tasks) {
+			Assert.assertFalse("Entity close failed too early.", task.get().isDone());
+		}
+		
+		Assert.assertTrue("Entity not closing even after calling close.", clientEntity.getIsClosingOrClosed());
+		Assert.assertFalse("Entity closed without sleeping.", clientEntity.getIsClosed());
+		
+		Thread.sleep(sleepInCloseDuration.toMillis() + 500); // 500 millis buffer
+		
+		Throwable failureException = null;
+		for (ForkJoinTask<CompletableFuture<Void>> task : tasks) {
+			CompletableFuture<Void> closeFuture = task.get();
+			Assert.assertTrue("Entity close didn't fail even after delay.", closeFuture.isDone());
+			try {
+				closeFuture.get();
+				Assert.fail("Entity close didn't fail.");
+			}catch (ExecutionException ex) {
+				Throwable cause = ex.getCause();
+				if (failureException == null) {
+					failureException = cause;
+				}
+				else
+				{
+					Assert.assertEquals("All concurrent close failures didn't fail with the same exception.", failureException, cause);
+				}
+			}
+		}
+	}
+	
+	class TestClientEntity extends ClientEntity {
+
+		private final Duration sleepDurationInClose;
+		private final int targetNumberOfCloseFailures;
+		private final boolean shouldSleepInFailure;
+		private AtomicInteger numberOfCloseFailures = new AtomicInteger(0);		
+		private AtomicInteger numberOfCloseCalls = new AtomicInteger(0);
+		
+		TestClientEntity(int targetNumberOfCloseFailures) {
+			this(targetNumberOfCloseFailures, Duration.ZERO);
+		}
+		
+		TestClientEntity(int targetNumberOfCloseFailures, Duration sleepDurationInClose) {
+			this(targetNumberOfCloseFailures, sleepDurationInClose, false);
+		}
+		
+		TestClientEntity(int targetNumberOfCloseFailures, Duration sleepDurationInClose, boolean shouldSleepInFailure) {
+			super(UUID.randomUUID().toString());
+			this.sleepDurationInClose = sleepDurationInClose;
+			this.targetNumberOfCloseFailures = targetNumberOfCloseFailures;
+			this.shouldSleepInFailure = shouldSleepInFailure;
+		}
+		
+		@Override
+		protected CompletableFuture<Void> onClose() {
+			numberOfCloseCalls.incrementAndGet();
+			if(numberOfCloseFailures.get() < targetNumberOfCloseFailures)
+			{
+				numberOfCloseFailures.incrementAndGet();
+				CompletableFuture<Void> failFuture = new CompletableFuture<>();
+				if (this.shouldSleepInFailure) {
+					if (this.sleepDurationInClose.isZero()) {
+						failFuture.completeExceptionally(new Exception("Close failed."));
+					} else {
+						Thread completionThread = new Thread(() -> {
+							try {
+								Thread.sleep(this.sleepDurationInClose.toMillis());
+							} catch (InterruptedException e) {
+								Thread.currentThread().interrupt();
+							}
+							
+							failFuture.completeExceptionally(new Exception("Close failed."));
+						});
+						
+						completionThread.start();
+					}
+				} else {
+					failFuture.completeExceptionally(new Exception("Close failed."));
+				}
+				
+				return failFuture;
+			}
+			else
+			{
+				if (this.sleepDurationInClose.isZero()) {
+					return CompletableFuture.completedFuture(null);
+				} else {
+					CompletableFuture<Void> closeFuture = new CompletableFuture<>();
+					
+					Thread completionThread = new Thread(() -> {
+						try {
+							Thread.sleep(this.sleepDurationInClose.toMillis());
+						} catch (InterruptedException e) {
+							Thread.currentThread().interrupt();
+						}
+						
+						closeFuture.complete(null);
+					});
+					
+					completionThread.start();
+					return closeFuture;
+				}
+			}
+		}
+		
+		int getTotalNumberOfCloseCalls() {
+			return this.numberOfCloseCalls.get();
+		}
+	}
+}