[UIMA-4830] UIMA-AS: refactor SharedConnection code in the client

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.8.1AS
• Component/s: Async Scaleout
• Assignee: Jaroslaw Cwiklik
• Reporter: Jaroslaw Cwiklik
• Created: 09/Mar/16 16:35
• Updated: 11/Mar/16 17:52
• Resolved: 11/Mar/16 17:52

Description

Current UIMA-AS client code uses single instance of a semaphore (sharedConnectionSemaphore) to guard access to JMS connections. The client code creates a connection for each broker url a client wants to use. So there may be multiple shared connections (one per broker URL) and one semaphore for all. If one of the shared connections hangs as recently observed when using failover://(...), other threads hang waiting for a semaphore to be released. The hang is caused by silent retry in AMQ connection.start(). This method does not return if broker is not accepting a connection and client uses failover protocol.
Modify client code to use different semaphore for each broker url. Failure to connect to one will not effect other connections (threads).
Also, add ExceptionListener to Connection object to receive notification on failures.