I'm confused as to whether a ServiceListener can be called on from multiple threads by the OSGi framework, say, if two service-related events occurred "at the same" time by different threads registering and unregistering services.
The question extends to ServiceTracker and its ServiceTrackerCustomizer: Can the addingService(), modifiedService(), and removedService() methods be called on concurrently, meaning that their operation must be made thread-aware? Section 6.1.21 of the OSGi R4 core specification reads: ,---- | When a ServiceEvent is fired, it is synchronously delivered to a | BundleListener. `---- Aside from it looking like "BundleListener" should probably be "ServiceListener", the sentence sounds like it's saying that only one ServiceEvent will be delivered to a ServiceListener at a time. Is that true? If so, can I also conclude that a ServiceTrackerCustomizer will only be called on by one thread at a time? I ask because the ServiceTrackerCustomizer implementation has some synchronized blocks that are attempting to protect some of its data against concurrent access, but the user-provided callback functions are called on outside of those synchronized regions. -- Steven E. Harris
