Currently there is too much complexity in the handling of client connections to the drivers and their status. In particular, each JPPFClientConnection implementation holds 2 actual connections, both subclasses of AbstractClientConnectionHandler and each with their status listeners. The main connection status is set either directly or as a combination of the states of the two "sub-connections". In the former case, the sub-connections status becomes inconsistent with that of the main connection.

Overall, this complexity results in many observed problems in the client, especially when running the automated tests: deadlocks, race conditions, failures of the recovery and failover mechanisms.

What we propose is to remove the code that handle the status in the sub-connections (and thus in AbstractClientConnectionHandler) and only keep one source of status and associated events.

Additionally, the abstract class org.jppf.client.balancer.ChannelWrapper, subclassed as ChannelWrapperLocal and ChannelWrapperRemote, holds an executor filed of type ExecutorService defined as a single thread executor in both subclasses. Instead of a separate thread pool for each ChannelWrapper, we should make use of the executor held by the JPPFClient instance, and add proper synchronization if needed.