[
https://jira.jboss.org/jira/browse/JGRP-659?page=com.atlassian.jira.plugi...
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Bela Ban commented on JGRP-659:
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Possible solution:
#1: install connections for new members only on a view change
#2 trash connections for all members on a merge view
#3 Use logical addresses:
- A logical address consists of
- a user-given (or generated) name, e.g. "X". This name stays with the
address from channel creation
to channel close
- a UUID. This is created on channel connect, deleted on channel disconnect and
re-created on channel
connect. This is used for equals() and hashCode() of the logical address. Since it
is re-created on
every connect(), it will prevent reincarnation issues. UUIDs are guaranteed to be
unique over time for
a given host. This is better than using address:port, because port is not
guaranteed to be unique over
time, especially when we use bind_port
Merge and UNICAST sequencing problem
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Key: JGRP-659
URL:
https://jira.jboss.org/jira/browse/JGRP-659
Project: JGroups
Issue Type: Bug
Affects Versions: 2.4, 2.5, 2.6
Reporter: Vladimir Blagojevic
Assignee: Bela Ban
Fix For: 2.8
Attachments: ConcurrentMemberTest.java
The problem is related to trashing of connection table in UNICAST during merge. Consider
following scenario:
There are 4 nodes in a cluster A,B,C, and D. After network split we have two islands A,B
and C,D. When the network healing starts eventually MergeView gets installed in both
islands. MergeView installation causes trashing of UNICAST connection table [1].
However if we have a scenario where MergeView gets installed in A,B island at time T and
it gets installed in island C,D at time T+N msec and a node from island A,B sends a
unicast message in this N msec time window then we'll run into problems with unicast
sequencing at C and D. Why? Because next message coming from island A,B into C,D will be
will with sequence number > 1 and sequencing in UNICAST of C,D after connection
trashing (from merge) expects starting sequence of 1. This causes UNICAST in C and/or D to
wait forever for missing messages. Final outcome is thus that no more unicast message
coming from A and/or B will ever be delivered at C and/or D!
[
1]http://jira.jboss.com/jira/browse/JGRP-348
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