[jboss-jira] [JBoss JIRA] (JGRP-1387) MERGE3: merging in large clusters

MERGE3: merging in large clusters --------------------------------- Key: JGRP-1387 URL: https://issues.jboss.org/browse/JGRP-1387 Project: JGroups Issue Type: Feature Request Reporter: Bela Ban Assignee: Bela Ban Fix For: 3.1 MERGE2 has the issue that concurrent merges are frequent with large clusters. MERGE3 will change this and works as follows: - Every node sends a multicast with its address, logical name, physical address and ViewId every N seconds - Every node collects this information and - every N * 1.5 seconds - determines (a) whether we have different ViewIds and (if so) (b) determines the merge leader from the collected info - The merge leader then collects the different Views from the merge participants, and sends a MERGE event up the stack, so that GMS can start the merge The benefits of MERGE3 are: - Good for large clusters, geared toward UDP based stacks - Only 1 merge in the cluster at any time - The collection of information to see whether a merge is needed is spaced out over a longer time period (N secs), compared to MERGE2, which uses Discovery.findAllViews(), which consists of a multicast and N unicasts. This might cause temporary congestion and packet loss - On a merge, the members already have the logical-physical address mapping (unlike MERGE2)