Synchronize ClientResources shutdown in client shutdown #475

Synchronize on the ClientResources.close()-Future when shutting down a redis client instance via AbstractRedisClient.shutdown(…). Previously the close future was not used to synchronize shutdown which might leave running threads after leaving AbstractRedisClient.shutdown(…).

Client shutdown may take longer because of synchronization. The client may be shut down faster by calling the appropriate shutdown method with the desired timeout/quiet period.

src/main/java/com/lambdaworks/redis/AbstractRedisClient.java

@@ -390,7 +390,8 @@ public void shutdown(long quietPeriod, long timeout, TimeUnit timeUnit) {
             }
 
             if (!sharedResources) {
-                clientResources.shutdown(quietPeriod, timeout, timeUnit);
+                Future<?> groupCloseFuture = clientResources.shutdown(quietPeriod, timeout, timeUnit);
+                closeFutures.add(groupCloseFuture);
             } else {
                 for (EventLoopGroup eventExecutors : eventLoopGroups.values()) {
                     Future<?> groupCloseFuture = clientResources.eventLoopGroupProvider().release(eventExecutors, quietPeriod,