@@ -1595,6 +1595,7 @@ final class PoolMaintainer {
 Instant lastResetTime = Instant.ofEpochMilli(0);
 int numSessionsToClose = 0;
 int sessionsToClosePerLoop = 0;
+boolean closed = false;
 
 @GuardedBy("lock")
 ScheduledFuture<?> scheduledFuture;
@@ -1621,17 +1622,26 @@ public void run() {
 
 void close() {
 synchronized (lock) {
-scheduledFuture.cancel(false);
-if (!running) {
-decrementPendingClosures(1);
+if (!closed) {
+closed = true;
+scheduledFuture.cancel(false);
+if (!running) {
+decrementPendingClosures(1);
+}
 }
 }
 }
 
+boolean isClosed() {
+synchronized (lock) {
+return closed;
+}
+}
+
 // Does various pool maintenance activities.
 void maintainPool() {
 synchronized (lock) {
-if (isClosed()) {
+if (SessionPool.this.isClosed()) {
 return;
 }
 running = true;
@@ -1643,7 +1653,7 @@ void maintainPool() {
 replenishPool();
 synchronized (lock) {
 running = false;
-if (isClosed()) {
+if (SessionPool.this.isClosed()) {
 decrementPendingClosures(1);
 }
 }
@@ -2126,6 +2136,7 @@ private void handleCreateSessionsFailure(SpannerException e, int count) {
 }
 if (isDatabaseOrInstanceNotFound(e)) {
 setResourceNotFoundException((ResourceNotFoundException) e);
+poolMaintainer.close();
 }
 }
 }
@@ -2161,10 +2172,14 @@ ListenableFuture<Void> closeAsync(ClosedException closedException) {
 }
 closureFuture = SettableFuture.create();
 retFuture = closureFuture;
-pendingClosure =
-totalSessions() + numSessionsBeingCreated + 1 /* For pool maintenance thread */;
 
-poolMaintainer.close();
+pendingClosure = totalSessions() + numSessionsBeingCreated;
+
+if (!poolMaintainer.isClosed()) {
+pendingClosure += 1; // For pool maintenance thread
+poolMaintainer.close();
+}
+
 sessions.clear();
 for (PooledSessionFuture session : checkedOutSessions) {
 if (session.Exception != null) {
@@ -2180,7 +2195,13 @@ ListenableFuture<Void> closeAsync(ClosedException closedException) {
 closeSessionAsync(session);
 }
 }
+
+// Nothing to be closed, mark as complete
+if (pendingClosure == 0) {
+closureFuture.set(null);
+}
 }
+
 retFuture.addListener(
 new Runnable() {
 @Override