long connect time in application that frequently closes and opens new channel ----------------------------------------------------------------------------- Key: JGRP-244 URL: http://jira.jboss.com/jira/browse/JGRP-244 Project: JGroups Issue Type: Bug Affects Versions: 2.2.8, 2.2.9, 2.3, 2.2.9.1, 2.2.9.2 Environment: SLES 9 Reporter: Bruce Schuchardt Assigned To: Bela Ban Fix For: 2.4 I have an application that has one long-lived jgroups member and four other processes that often close their channel and create a new one. Most of the time these new connections are formed in a dozen milliseconds or so, but sometimes they're taking over 20 seconds. The apps are using TCPGOSSIP with multicast turned off. I turned on tracing and saw that the coordinator's UNICAST was having some trouble. It got a message from a departed member that it stored up and dispatched later when the departed member's address was reused by a new channel. a) A member left the view and UNICAST removed its connection for the member and added it to previous_members. b) Another message then arrived from the member, and UNICAST created a new connection for it. The message had seqno 4, and was put in the AckReceiverWindow and not passed up. c) A few seconds later, a process created a new channel and it got the same ID as the one the coordinator's UNICAST just dealt with. d) The new channel sent three UNICAST messages to the coordinator. On the third message, the coordinator's UNICAST removed #3 and the old #4 and passed them both up. e) The new channel sent message #4, a JOIN_REQ, and UNICAST discarded it The new channel eventually goes through discovery again and gets into the group, but it adds quite a bit to channel startup time, and I'm a little worried that there might be a case where a much higher seqno gets trapped in the receiver window like this. I fixed this for my needs by changing UNICAST.handleDataReceived to reject a previous_member message if the seqno is higher than the default initial seqno, but I suppose that might wreak havoc with some other algorithms. private void handleDataReceived(Object sender, long seqno, Message msg) { if(trace) log.trace(new StringBuffer().append(local_addr).append(" <-- DATA(").append(sender).append(": #").append(seqno)); if(previous_members.contains(sender)) { // we don't want to see messages from departed members if (seqno > DEFAULT_FIRST_SEQNO) { if (trace) log.trace("discarding message " + seqno + " from previous member " + sender); return; } if(trace) log.trace("removed " + sender + " from previous_members as we received a message from it"); previous_members.removeElement(sender); } Entry entry; synchronized(connections) {