[ISSUE #762]fix defaultAsyncSenderExecutor not shutdown when...

 [ISSUE #762]fix defaultAsyncSenderExecutor not shutdown when DefaultMQProducerImpl shutdown. (#880)

[ISSUE #762 ]fix defaultAsyncSenderExecutor not shutdown when DefaultMQProducerImpl shutdown.

client/src/main/java/org/apache/rocketmq/client/impl/producer/DefaultMQProducerImpl.java

@@ -236,6 +236,7 @@ public class DefaultMQProducerImpl implements MQProducerInner {
                 break;
             case RUNNING:
                 this.mQClientFactory.unregisterProducer(this.defaultMQProducer.getProducerGroup());
+                this.defaultAsyncSenderExecutor.shutdown();
                 if (shutdownFactory) {
                     this.mQClientFactory.shutdown();
                 }