[jboss-jira] [JBoss JIRA] Resolved: (JGRP-341) Extend FLUSH to fully support virtual synchrony

Extend FLUSH to fully support virtual synchrony ----------------------------------------------- Key: JGRP-341 URL: http://jira.jboss.com/jira/browse/JGRP-341 Project: JGroups Issue Type: Feature Request Affects Versions: 2.4 Reporter: Bela Ban Assigned To: Vladimir Blagojevic Priority: Critical Fix For: 2.5 Currently, FLUSH makes sure that all members 'flush' their pending messages and then stop sending new ones until the join or state transfer is over. However, FLUSH does *not* (unlike the old version) make sure that - on JOIN - all members have seen the same set of messages before installing a new view. Example: P sends M, but immediately after sending M crashes. If another member Q received M, but R didn't see M, then - with the current FLUSH - R will *not* see M. We need to run a messages exchange phase, as part of FLUSH, which makes sure that all member have seen the same set of messages in the same view, before installing a new view. Whether to run this or not could be made configurable. If enabled, we could piggyback the message exchange on START_FLUSH/FLUSH_OK etc. A simple (but costly) solution would be to simply multicast all messages received from other members before multicasting the FLUSH_OK. A better solution would be to exchange digests with highest sequence numbers seen for all members, and then only multicast the missing messages. This *might* require an additional phase though.