Infinispan can miss incoming commands with JGroupsChannelLookup --------------------------------------------------------------- Key: ISPN-6322 URL: https://issues.jboss.org/browse/ISPN-6322 Project: Infinispan Issue Type: Bug Components: Core Affects Versions: 8.2.0.CR1, 8.1.2.Final Reporter: Dan Berindei Assignee: Dan Berindei Fix For: 8.2.1.Final, 9.0.0.Alpha1, 9.0.0.Final Normally, the JGroupsTransport startup sequence goes like this: # Create the {{Channel}} # Create the {{CommandAwareRpcDispatcher}} and install it as an {{UpHandler}} # Connect the channel This way, every {{RequestCorrelator}} message received by the channel is passed up to {{CommandAwareRpcDispatcher}}, which executes the appropriate command. When using a {{JGroupsChannelLookup}}, the lookup implementation is allowed to return a {{Channel}} instance that is already connected ({{shouldConnect() == false}}). That means there is now a window where the channel doesn't have an {{UpHandler}}, and messages sent to this node are discarded. Normally a node only receives commands after it sent a join request to the coordinator. There are however a few exceptions: # On startup, {{LocalTopologyManagerImpl}} sends the join request to the JGroups coordinator, which may not have the {{UpHandler}} yet. This seems to be responsible for the recent hanging in {{ConcurrentStartTest}}. We have a workaround here, to use a smaller timeout on the {{CacheTopologyControlCommand(JOIN)}} command, and retry it on {{TimeoutException}}. # When a node becomes coordinator, {{ClusterTopologyManagerImpl}} broadcasts a {{GET_STATUS}} request to all cluster members, and expects a response from each of them. The same workaround with a smaller timeout and retries might work here. # In replicated mode, write commands are broadcasted to all cluster members. There is some commented out code in {{RpcManagerImpl.invokeRemotelyAsync()}} that might fix it by only waiting for responses from the cache topology members. We should consider deprecating {{JGroupsChannelLookup.shouldConnect()}} and requiring that the channel is only connected by {{JGroupsTransport}}. Assuming that works with {{ForkChannel}}, of course.