Check if pull message service has shutdown before scheduling pull requests (#277)

client/src/main/java/org/apache/rocketmq/client/impl/consumer/PullMessageService.java

@@ -44,13 +44,16 @@ public class PullMessageService extends ServiceThread {
     }
 
     public void executePullRequestLater(final PullRequest pullRequest, final long timeDelay) {
+        if (!isStopped()) {
             this.scheduledExecutorService.schedule(new Runnable() {
-
                 @Override
                 public void run() {
                     PullMessageService.this.executePullRequestImmediately(pullRequest);
                 }
             }, timeDelay, TimeUnit.MILLISECONDS);
+        } else {
+            log.warn("PullMessageServiceScheduledThread has shutdown");
+        }
     }
 
     public void executePullRequestImmediately(final PullRequest pullRequest) {
@@ -62,7 +65,11 @@ public class PullMessageService extends ServiceThread {
     }
 
     public void executeTaskLater(final Runnable r, final long timeDelay) {
+        if (!isStopped()) {
             this.scheduledExecutorService.schedule(r, timeDelay, TimeUnit.MILLISECONDS);
+        } else {
+            log.warn("PullMessageServiceScheduledThread has shutdown");
+        }
     }
 
     public ScheduledExecutorService getScheduledExecutorService() {
@@ -86,10 +93,8 @@ public class PullMessageService extends ServiceThread {
         while (!this.isStopped()) {
             try {
                 PullRequest pullRequest = this.pullRequestQueue.take();
-                if (pullRequest != null) {
                 this.pullMessage(pullRequest);
-                }
-            } catch (InterruptedException e) {
+            } catch (InterruptedException ignored) {
             } catch (Exception e) {
                 log.error("Pull Message Service Run Method exception", e);
             }