[infinispan-dev] NPE from invokeRemotely on stopped cache

[Sanne Grinovero]

Hello,
I got the following stacktrace using CR2:
     [exec] java.lang.NullPointerException
     [exec] 	at
org.infinispan.remoting.rpc.RpcManagerImpl.invokeRemotely(RpcManagerImpl.java:92)
     [exec] 	at
org.infinispan.remoting.rpc.RpcManagerImpl.invokeRemotely(RpcManagerImpl.java:128)
     [exec] 	at
org.infinispan.remoting.ReplicationQueue.flush(ReplicationQueue.java:147)
     [exec] 	at
org.infinispan.remoting.ReplicationQueue$1.run(ReplicationQueue.java:99)
     [exec] 	at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
     [exec] 	at
java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
     [exec] 	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
     [exec] 	at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
     [exec] 	at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:181)
     [exec] 	at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:205)
     [exec] 	at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
     [exec] 	at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
     [exec] 	at java.lang.Thread.run(Thread.java:619)

>From which I went to inspect
org.infinispan.remoting.transport.jgroups.JGroupsTransport; in this
class the "members" field is initialized as Collections.emptyList()
and it appears that the only way to become null is by stopping the
cache.
Also it seems that in many points the check "members!=null" is
performed, but not in RpcManagerImpl.

Could the stop() method be changed to set this value to emptyList()
too, so that all those "!=null" checks could be avoided, or if you see
good reasons to throw an error then what would be a better one than
NPE.

I'm also wondering if this is supposed to happen: isn't this a race
condition during the stop process of the cache? I'd like to stop it
after all replications have been sent, seems cleaner.

Regards,
Sanne