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Posted to issues@activemq.apache.org by "Krzysztof Porebski (Jira)" <ji...@apache.org> on 2019/09/08 22:50:00 UTC
[jira] [Updated] (AMQNET-610) Race condition during consumer
creation
[ https://issues.apache.org/jira/browse/AMQNET-610?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Krzysztof Porebski updated AMQNET-610:
--------------------------------------
Summary: Race condition during consumer creation (was: Race condition during consumer creation and shutdown)
> 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
>
> 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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