[jira] [Commented] (AMQNET-610) Race condition during consumer creation

["ASF subversion and git services (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AMQNET-610?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16927725#comment-16927725 ] 

ASF subversion and git services commented on AMQNET-610:
--------------------------------------------------------

Commit d5c0542896c0394af49daf69c4f9327035779032 in activemq-nms-amqp's branch refs/heads/master from Havret
[ https://gitbox.apache.org/repos/asf?p=activemq-nms-amqp.git;h=d5c0542 ]

AMQNET-610: Race condition during consumer creation


> Race condition during consumer creation
> ---------------------------------------
>
>                 Key: AMQNET-610
>                 URL: https://issues.apache.org/jira/browse/AMQNET-610
>             Project: ActiveMQ .Net
>          Issue Type: Bug
>          Components: AMQP, NMS
>            Reporter: Krzysztof Porebski
>            Priority: Critical
>          Time Spent: 2h
>  Remaining Estimate: 0h
>
> Working on CI I found a race condition that reveals itself on slower machines and may result in losing messages by consumers. 
> The race condition is a result of treating the creation of consumer resources and starting them as an atomic operation:
> {code:java}
> public async Task Init()
> {
>     await Session.Connection.CreateResource(Info);
>     await Session.Connection.StartResource(Info);
> }
> {code}
> On slower boxes pending message may be delivered to the provider before above code returns:
> {code:java}
> public IMessageConsumer CreateConsumer(IDestination destination, string selector, bool noLocal)
> {
>     CheckClosed();    NmsMessageConsumer messageConsumer = new NmsMessageConsumer(consumerIdGenerator.GenerateId(), this, destination, selector, noLocal);
>     messageConsumer.Init().ConfigureAwait(false).GetAwaiter().GetResult();
> // here may be a race condition    
> consumers.TryAdd(messageConsumer.Info.Id, messageConsumer);
>     
>     return messageConsumer;
> }
> {code}
> If message arrives before `Init` returns (which means before newly created consumer is added to the list of available consumers), the message will be ignored. 
> {code:java}
> public void OnInboundMessage(InboundMessageDispatch envelope)
> {
>     if (consumers.TryGetValue(envelope.ConsumerInfo.Id, out NmsMessageConsumer messageConsumer))
>     {
>         messageConsumer.OnInboundMessage(envelope);
>     }
> }
> {code}
>  
>  
>  



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