UNICAST: skipping of seqnos --------------------------- Key: JGRP-1807 URL: https://issues.jboss.org/browse/JGRP-1807 Project: JGroups Issue Type: Bug Reporter: Bela Ban Assignee: Bela Ban Fix For: 3.2.13, 3.5 {noformat} The log starts with: 10-Mar-2014 13:21:47 WARN [org.jgroups.protocols.UNICAST2] (OOB-105,shared=tcp) node1/web: (requester=node2/web) message node2/web::1511786 not found in retransmission table of node2/web: [1511785 | 1511785 | 1511857] (53 elements, 19 missing) The numbers are 1511786-1511804 for "not found in retransmission...." And end: 10-Mar-2014 14:48:26 WARN [org.jgroups.protocols.UNICAST2] (OOB-118,shared=tcp) node1/web: (requester=node2/web) message node2/web::1511804 not found in retransmission table of node2/web: [1511785 | 1511785 | 1514802] (2998 elements, 19 missing) {noformat} It seems that node1 is missing messages 1511785-1511804 which it sent to node2. Since a null message cannot be added to the sender table (due to the {{msg.isFlagSet()}} which would throw an NPE), I asume we're skipping a seqno: In {{UNICAST}}, {{UNICAST2}} and {{UNICAST3}} {{down()}}, if a seqno is skipped, we get endless retransmissions. Example: * We get the next seqno 1, add the message to the table and send it * We get the next seqno 2. However, if {{running}} is false, we don't add the message * We get the next seqno 3. Now {{running}} is true, and we add 3 to the table --> Now we have a missing message 2 which will always be null as it hasn't been added to the table This is highly unlikely, as I haven't been able to find a scenario where running flips from true to false to true quickly. If it flips from true to false, this is because {{stop()}} has been called. Also, in {{down()}}, we actually check {{running}} and return if false. In this scenario, the connections are all removed, so seqno is reset to 1. Anyway, I'm going to replace the {{while(running)}} loop with a {{do while(running)}} loop, so we always add the message to the table, even if running=false. [1] https://github.com/belaban/JGroups/blob/Branch_JGroups_3_2/src/org/jgroup...