[BUG] DefaultServiceBusNamespaceProcessorFactory doesn't remove disposed/closed ServiceBusProcessorClients from processorMap cache

[stephenstachelski-tr]

Describe the bug
The DefaultServiceBusNamespaceProcessorFactory fails to clean up closed processors from its internal cache, causing it to return non-functional processors.

Problem Details:

1. When a ServiceBusProcessorClient is disposed or closed, it remains in the factory's processorMap cache
2. Subsequent calls to createProcessor() retrieve these closed processors from the cache
3. These closed processors cannot process messages from the queue
4. The processorMap is only cleared when the factory itself is disposed, not when individual processors are closed

Impact:

• Message processing fails silently because the factory returns cached processors that are no longer operational.

Exception or Stack Trace
No stack trace

To Reproduce

• Create processor by calling one of the create methods
• Dispose/close the processor (simulating a non transient error that closes the processor)
• Call createProcessor and the disposed/closed processor is returned

Code Snippet
DefaultServiceBusNamespaceProcessorFactory.java#doCreateProcessor

The below snippet shows that the return for doCreateProcessor is either a value from the cache (which is never cleared or pruned) or it creates a new processor

`
private ServiceBusProcessorClient doCreateProcessor(String name,
@nullable String subscription,
@nonnull MessageListener<?> messageListener,
@nonnull ServiceBusErrorHandler errorHandler,
@nullable ProcessorProperties properties) {
ConsumerIdentifier key = new ConsumerIdentifier(name, subscription);

    return processorMap.computeIfAbsent(key, k -> {
        ProcessorPropertiesParentMerger propertiesMerger = new ProcessorPropertiesParentMerger();
        ProcessorProperties processorProperties = propertiesMerger.merge(properties, this.namespaceProperties);
        processorProperties.setEntityName(k.getDestination());
        if (!k.hasGroup()) {
            processorProperties.setEntityType(ServiceBusEntityType.QUEUE);
        } else {
            processorProperties.setEntityType(ServiceBusEntityType.TOPIC);
            processorProperties.setSubscriptionName(k.getGroup());
        }
  ...

`

Expected behavior
The factory should either:

• Remove processors from processorMap when they are closed/disposed, OR
• Detect closed processors and create new ones when createProcessor() is called

Setup (please complete the following information):

• OS: Windows/WSL Ubuntu 22.04.5
• IDE: Intellij
• Library/Libraries: com.azure.spring:spring-messaging-azure-servicebus:5.24.1
• Java version: 17
• App Server/Environment: Tomcat
• Frameworks: Spring

Additional context
In our environment, we noticed that over time, messages would stop being consumed from the queues. We tried stopping and starting the listeners, but the only thing that worked was restarting the application. Stepping through the code we noticed the processors were disposed/closed and that no matter what we did, we could not get the factory to return a non disposed processor.

As a workaround, we used reflection to access the processor map and clear it when we detected the processors were closed so that the factory would create new processors when we stopped and started the messageListener.

Information Checklist
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• Bug Description Added
• Repro Steps Added
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[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @EldertGrootenboer @skarri-microsoft.