[jboss-jira] [JBoss JIRA] (JGRP-1484) SEQUENCER and merge-views broken

SEQUENCER and merge-views broken -------------------------------- Key: JGRP-1484 URL: https://issues.jboss.org/browse/JGRP-1484 Project: JGroups Issue Type: Bug Affects Versions: 3.0.10 Reporter: David Hotham Assignee: Bela Ban Fix For: 3.1 Here's a new way in which putting SEQUENCER below GMS is broken. Start with A having view B|4 [B,A], while B, C and D all have view B|7 [B,C,D]. Now we start a merge, in which B is coordinator. B creates the view C|8 [C, D, A, B]. (I've opened a pull request saying that B surely shouldn't issue a view where the ViewID says that C was the creator. But I think that this is incidental, and not key to the bug that I'm reporting here). Now B sends INSTALL_MERGE_VIEW to B (a coordinator) and A (a merge participant, per Util.determineMergeParticipants). B gets this first and broadcasts the new view to [B, C, D]. In particular, B is now not a coordinator. Then A gets the INSTALL_MERGE_VIEW, and it too tries broadcasting the new view. SEQUENCER gets involved, and forwards the broadcast to B (as the coordinator in the old view). B discards this; it's no longer a coordinator. So the new view is not installed at A. All future broadcasts from A are forwarded to B, who discards them. The group is fractured, and none of A's broadcasts are delivered. I'm not sure what the right fix would be. I wonder whether things should be arranged so that in a merge: - coordinators behave as today, broadcasting the new view to their own sub-groups - but mere participants do not do this: they should just have the new view installed on them.