Env: Hardware: 2 x86 based machines OS: Suse Linux Enterprise Server 9 SP3 Server: JBoss 4.0.5.GA JGroups : 2.4.1 We're running a performance test on the cluster above. 100 concurrent virtual users with 1 second pause time between actions. After sometime (4hours) in the test I observed the following error on the server console. | 2007-02-16 17:12:32,294 ERROR [org.jgroups.protocols.pbcast.NAKACK:error] (requester=-.-.-.205:33509, local_addr=-.-.-.205:33509) message -.-.-.205:33509::1172743 not found in sent msgs. | Sent messages: [1172262 - 1172861] (600) | 2007-02-16 17:44:39,599 ERROR [org.jgroups.protocols.pbcast.NAKACK:error] (requester=-.-.-.205:33509, local_addr=-.-.-.205:33509) message -.-.-.205:33509::1628057 not found in sent msgs. | Sent messages: [1627729 - 1628398] (670) | Note: I omitted the servers subnet for security reasons. The errors above occur not freqently (once or twice every 4 hours) on the servers but I'd like to understand why they happen. It looks to me like a concurrency issue with NAKACK when looking at the code base for JGroups 2.4.1. Can someone explain the error? Thanks, View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4020142#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...