[jira] [Created] (ROCKETMQ-107) Access ServiceState is not thread safe when start() or shutdown()

["Jaskey Lam (JIRA)" <ji...@apache.org>]

Jaskey Lam created ROCKETMQ-107:
-----------------------------------

             Summary: Access ServiceState is not thread safe when start() or shutdown()
                 Key: ROCKETMQ-107
                 URL: https://issues.apache.org/jira/browse/ROCKETMQ-107
             Project: Apache RocketMQ
          Issue Type: Bug
          Components: rocketmq-client
            Reporter: Jaskey Lam
            Assignee: Xiaorui Wang
            Priority: Minor


When start() or shutdown(), service's state is not thread safe which may break happen-before.

For example: 

        switch (this.serviceState) {
            case CREATE_JUST:
                log.info("the consumer [{}] start beginning. messageModel={}, isUnitMode={}", this.defaultMQPushConsumer.getConsumerGroup(),
                    this.defaultMQPushConsumer.getMessageModel(), this.defaultMQPushConsumer.isUnitMode());
                this.serviceState = ServiceState.START_FAILED;
                ..// do some start job here
                this.serviceState = ServiceState.RUNNING;
                break;
            case RUNNING:
            case START_FAILED:
            case SHUTDOWN_ALREADY:
                throw new MQClientException("The PushConsumer service state not OK, maybe started once, "//
                    + this.serviceState//
                    + FAQUrl.suggestTodo(FAQUrl.CLIENT_SERVICE_NOT_OK),
                    null);
            default:
                break;
        }

1. If the user is start twice in two thread, the resources may initize twice.
2. if the user start in threadA and shutdown very quicky in another thread B, shutdown may not reclaim the resources.

Though the sceniro is very uncommon, but it is indeed a bug here. Fix is actually quite trivial.



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