@@ -1250,25 +1250,27 @@ public void prepareReadWriteTransaction() {
 
 @Override
 public void close() {
-synchronized (lock) {
-Exception = null;
-checkedOutSessions.remove(this);
-}
-PooledSession delegate = getOrNull();
-if (delegate != null) {
-delegate.close();
+try {
+asyncClose().get();
+} catch (InterruptedException e) {
+throw SpannerExceptionFactory.propagateInterrupt(e);
+} catch (ExecutionException e) {
+throw SpannerExceptionFactory.asSpannerException(e.getCause());
 }
 }
 
 @Override
 public ApiFuture<Empty> asyncClose() {
-synchronized (lock) {
-Exception = null;
-checkedOutSessions.remove(this);
-}
-PooledSession delegate = getOrNull();
-if (delegate != null) {
-return delegate.asyncClose();
+try {
+PooledSession delegate = getOrNull();
+if (delegate != null) {
+return delegate.asyncClose();
+}
+} finally {
+synchronized (lock) {
+Exception = null;
+checkedOutSessions.remove(this);
+}
 }
 return ApiFutures.immediateFuture(Empty.getDefaultInstance());
 }
@@ -1777,7 +1779,8 @@ private enum Position {
 private final Set<PooledSession> allSessions = new HashSet<>();
 
 @GuardedBy("lock")
-private final Set<PooledSessionFuture> checkedOutSessions = new HashSet<>();
+@VisibleForTesting
+final Set<PooledSessionFuture> checkedOutSessions = new HashSet<>();
 
 private final SessionConsumer sessionConsumer = new SessionConsumerImpl();
 

@@ -69,6 +69,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -534,13 +535,18 @@ public void testAsyncTransactionManagerCommitWithTag() {
 
 @Test
 public void singleUse() {
-DatabaseClient client =
-spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+DatabaseClientImpl client =
+(DatabaseClientImpl)
+spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
+assertThat(checkedOut).isEmpty();
 try (ResultSet rs = client.singleUse().executeQuery(SELECT1)) {
 assertThat(rs.next()).isTrue();
+assertThat(checkedOut).hasSize(1);
 assertThat(rs.getLong(0)).isEqualTo(1L);
 assertThat(rs.next()).isFalse();
 }
+assertThat(checkedOut).isEmpty();
 }
 
 @Test
@@ -2097,4 +2103,71 @@ public void testAsyncTransactionManagerCommitWithPriority() {
 assertNotNull(request.getRequestOptions());
 assertEquals(Priority.PRIORITY_HIGH, request.getRequestOptions().getPriority());
 }
+
+@Test
+public void singleUseNoAction_ClearsCheckedOutSession() {
+DatabaseClientImpl client =
+(DatabaseClientImpl)
+spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
+assertThat(checkedOut).isEmpty();
+
+// Getting a single use read-only transaction and not using it should not cause any sessions
+// to be stuck in the map of checked out sessions.
+client.singleUse().close();
+
+assertThat(checkedOut).isEmpty();
+}
+
+@Test
+public void singleUseReadOnlyTransactionNoAction_ClearsCheckedOutSession() {
+DatabaseClientImpl client =
+(DatabaseClientImpl)
+spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
+assertThat(checkedOut).isEmpty();
+
+client.singleUseReadOnlyTransaction().close();
+
+assertThat(checkedOut).isEmpty();
+}
+
+@Test
+public void readWriteTransactionNoAction_ClearsCheckedOutSession() {
+DatabaseClientImpl client =
+(DatabaseClientImpl)
+spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
+assertThat(checkedOut).isEmpty();
+
+client.readWriteTransaction();
+
+assertThat(checkedOut).isEmpty();
+}
+
+@Test
+public void readOnlyTransactionNoAction_ClearsCheckedOutSession() {
+DatabaseClientImpl client =
+(DatabaseClientImpl)
+spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
+assertThat(checkedOut).isEmpty();
+
+client.readOnlyTransaction().close();
+
+assertThat(checkedOut).isEmpty();
+}
+
+@Test
+public void transactionManagerNoAction_ClearsCheckedOutSession() {
+DatabaseClientImpl client =
+(DatabaseClientImpl)
+spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
+assertThat(checkedOut).isEmpty();
+
+client.transactionManager().close();
+
+assertThat(checkedOut).isEmpty();
+}
 }