Wrong use of "scheduleAtFixedRate" in consumer client code

[MatrixHB]

In consumer client code ConsumeMessageConcurrentlyService, there is a scheduled executor used to clean the expired messages(consuming-blocked messages) in ProcessQueue.

this.cleanExpireMsgExecutors.scheduleAtFixedRate(new Runnable() {

            @Override
            public void run() {
                cleanExpireMsg();
            }

        }, this.defaultMQPushConsumer.getConsumeTimeout(), this.defaultMQPushConsumer.getConsumeTimeout(), TimeUnit.MINUTES);

When using scheduleAtFixedRate, once a thread throws an exception, it will not continue to execute the following threads. So the Runnable must be surrounded by try-catch.

Since the scheduleAtFixedRate without try-catch, the cleanExpireMsg thread may abnormally exit and never be executed again, which may cause the consuming-blocked message always stay in ProcessQueue, resulting in the consume offset get stuck. （We have actually met this problem in production environment.）