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

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ROCKETMQ-107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15879784#comment-15879784 ] 

ASF GitHub Bot commented on ROCKETMQ-107:
-----------------------------------------

GitHub user Jaskey opened a pull request:

    https://github.com/apache/incubator-rocketmq/pull/68

    [ROCKETMQ-107] fix possible concurrency problem on ServiceState when consumer start/shutdown

    JIRA: https://issues.apache.org/jira/browse/ROCKETMQ-107

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/Jaskey/incubator-rocketmq ROCKETMQ-107-synchroization-on-ServiceState

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-rocketmq/pull/68.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #68
    
----
commit 91c41dae09405be95ed9ad8696959f79683dfd31
Author: Jaskey <li...@gmail.com>
Date:   2017-02-23T03:06:32Z

    [ROCKETMQ-107] fix possible concurrency problem on ServiceState when  consumer start/shutdown

----


> 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: Jaskey Lam
>            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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