We have an application which performs polling task to a SwiftMQ network,
i.e., issuing CLI commands to collect some statistics periodically. A
persistent connection need to be created and maintained; in event of
connectivity disruption, the application will try to reconnect to the
network, in a way transparently to the polling task.

SwiftMQ CLI API is used for establishing/maintaining connectivity with
SwiftMQ network. However, a problem was encountered: the CLI hangs after
some reconnect! Take a router named "router1s45" as example: the
application can switch to the router (i.e. CLI command of "sr
router1s45" succeeds), but then the CLI hangs there till the connection
is closed (when the router is rebooted) ...

Some notes:

• 
  For testing, the router "router1s45" is being started/stopped purposely
  for a few times to test reconnect.
  
  
  
  
  
• 
  If there is only one router in the network, then everything is fine and
  CLI never hangs. When there are more than one router (either in the same
  host or in different host), however, the CLI will hang after a few
  times' reconnect. The behaviour is a bit of random: sometimes after the
  first reconnect, sometimes after a few times' reconnect; sometimes for
  the first polling after reconnect, sometimes after a few times' polling
  for the same connection ...
  
  
  
  
  
• 
  It's found that there is always a ERROR log on the other router (not the
  router being started/stopped) when the CLI hangs. For example, two
  routers are in the host "s45", which are named as "router1s45",
  "router2s45" respectively. "router1s45" is being stopped/started for a few
  times, while "router2s45" is started all the time. Below is the error log
  for router "router2s45" when the CLI hangs:
  
  
  
  
  2005-01-10 16:31:44.387/sys$mgmt/ERROR/v400/DispatcherImpl, started=true, queueName=tmp$3@router1s45/visit, event: [ClientRequest, queueName=tmp$3@router1s45, length=29], exception: java.lang.NullPointerException: com.swiftmq.mgmt.protocol.v400.ProtocolFactory.createDumpable(0) returns null
  

Got any idea about why? Any suggestion/comments are appreciated!