[CAMEL-10707] Throttling policy is broken because service suspension/resume is not symmetric

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.19.0
• Component/s: camel-core
• Estimated Complexity: Unknown
• Assignee: Nicola Ferraro
• Reporter: Nicola Ferraro
• Created: 14/Jan/17 18:03
• Updated: 17/Jan/17 10:53
• Resolved: 17/Jan/17 10:53

Description

Camel ServiceHelper suspends and resumes services in a wrong way:

• Resume: https://github.com/apache/camel/blob/camel-2.18.1/camel-core/src/main/java/org/apache/camel/util/ServiceHelper.java#L313
• Suspend: https://github.com/apache/camel/blob/camel-2.18.1/camel-core/src/main/java/org/apache/camel/util/ServiceHelper.java#L384

When suspending a service, Camel checks if the service is implementing the Suspendable (marker) interface, while that interface is ignored when resuming it.

If you take a non Suspendable service like the TimerConsumer (it is not Suspendable but it is a SuspendableService, like many others...), the ServiceHelper will call the "stop()" method when suspending it, and the "resume()" method when resuming it. Practically it'll remain stopped ("resume()" is not implemented in > 90% of the components), since "start()" should be called after a stop operation.

So the ThrottlingInflightRoutePolicy, that suspends a route when there are too many exchanges and resumes it when they get lower than a threshold, is broken for many components (the route is stopped, but it's never restarted correctly).