Circuit Breaker issue

[t11omas]

When the Circuit breaker is tripped, is it meant to stop messages from being consumed from the queue, or does the move all messages onto the DLQ?

It isn't clear from the documentation, and I am playing around with this feature, and it appears all my messages for direct to the DLQ.

[zarusz]

It should stop the consumers when sufficent failure rate is reached, to avoid them all going to the DLQ. That said some portion of the messages during the transition period would go into the DLQ before the consumer is fully stopped.

Feel free to make the documentation clearer there (PR).

Post your findings and if you see opportunities for improvements.

[t11omas]

Thanks for the info.

It doesn't appear to be working as expected. It does log saying the Circuit breaker has been tripped but if I wait a while and then fire messages at it, they just go onto the DLQ.

I have just implemented my own Circuit breaker (a simplified version of what you did) and that works great.

[zarusz]

Did you check if the standard one stops the consumers?
Can you contribute your version? Is it based on health checks too?

[t11omas]

I could not get the circuit break nuget version to stop the consumers

My version is based on the healthchecks, but its not generic, inside our publisher, I just grab the bus and call stop and start on it based on the health status

Its not as nice to configure as you have it, but it does the job

[zarusz]

Lets make a bug from this issue for the RabbitMq + CircuitBreaker combination. I will have a look then. It should work. There are integration tests that sugest the consumers are being stopped when the breaker is triped.

Can you share the logs? It will be helpful.

[t11omas]

I am using SQS. Tomorrow morning I will see if I can create a sample Project to replicate it, as this might help me identify if it's a specific setting or combination of settings that is causing the issue Sent from Outlook for Android<https://aka.ms/AAb9ysg>

…

________________________________ From: Tomasz Maruszak ***@***.***> Sent: Tuesday, February 24, 2026 5:24:13 PM To: zarusz/SlimMessageBus ***@***.***> Cc: t11omas ***@***.***>; State change ***@***.***> Subject: Re: [zarusz/SlimMessageBus] Circuit Breaker (with RMQ) (Issue #454) Reopened #454<#454>. — Reply to this email directly, view it on GitHub<#454 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ADKMTTGWWAKRQTPD2UT6BLT4NSCL3AVCNFSM6AAAAACV6EUJVCVHI2DSMVQWIX3LMV45UABCJFZXG5LFIV3GK3TUJZXXI2LGNFRWC5DJN5XDWMRTGA2DENBZG42TGNI>. You are receiving this because you modified the open/close state.Message ID: ***@***.***>

[t11omas]

I believe I have worked out what is happening:

 messageBusBuilder
     .AddCompressedJsonSerializer()
     .AutoStartConsumersEnabled(options.AutoStartConsumers)
     .Consume<ResourceEvent<CustomsDeclarationEvent>>(x =>
         x.WithConsumer<ClearanceDecisionConsumer>()
             .Queue(options.ResourceEventsQueueName)
             .Instances(options.ConsumersPerHost)
             .VisibilityTimeout(options.VisibilityTimeout)
             .WhenUndeclaredMessageTypeArrives(x =>
             {
                 x.Log = true;
                 x.Fail = false;
             })
             .PauseOnDegradedHealthCheck("HMRC_CDS")
             .Filter(
                 (headers, message) =>
                     headers != null
                     && headers.TryGetValue("ResourceType", out var v)
                     && (string)v == ResourceEventResourceTypes.CustomsDeclaration
             )
     )
     .Consume<ResourceEvent<ProcessingErrorEvent>>(x =>
         x.WithConsumer<ProcessingErrorConsumer>()
             .Queue(options.ResourceEventsQueueName)
             .Instances(options.ConsumersPerHost)
             .VisibilityTimeout(options.VisibilityTimeout)
             .WhenUndeclaredMessageTypeArrives(x =>
             {
                 x.Log = true;
                 x.Fail = false;
             })
             .PauseOnDegradedHealthCheck("HMRC_CDS")
             .Filter(
                 (headers, message) =>
                     headers != null
                     && headers.TryGetValue("ResourceType", out var v)
                     && (string)v == ResourceEventResourceTypes.ProcessingError
             )
     );

So this sets up 2 consumer settings.

Then in the CircuitBreakerConsumerInterceptor it does this:

var bus = consumer.Settings[0].MessageBusSettings.Name ?? "default";

This only effects the first consumer, so the bus is still running and 1 consumer is still running.

Because 1 consumer is still running and its not failing undeclared messages, it just moves it direct to the DLQ.

[t11omas]

The reason my workaround worked, was because I was stopping the bus, to individual consumers, so that make sense why mines worked by the current approach within SMB doesn't work. So yes its a bug.