[jboss-jira] [JBoss JIRA] Commented: (JGRP-1043) UNICAST: high contention
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https://jira.jboss.org/jira/browse/JGRP-1043?page=com.atlassian.jira.plug...
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Brian Stansberry commented on JGRP-1043:
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Further to the above comment, the issue of setting "lowest" to a lower number
doesn't just apply to the case of acks of retransmissions. ACKs are issued in
sequence, but very well may not be received in sequence.
For anyone watching this JIRA, please understand that the issue I'm discussing on
this/previous comment is not the main focus of this JIRA; it's a small side aspect
Bela asked me to document here.
UNICAST: high contention
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Key: JGRP-1043
URL: https://jira.jboss.org/jira/browse/JGRP-1043
Project: JGroups
Issue Type: Task
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 2.6.13, 2.8
If UNICAST receives a high number of messages *and* sends a high number of messages
concurrently, there will be a lot of retransmissions. Reason is contention on
'connections', with up- and down messages accessing it concurrently. Both up- and
down- messages impede each other and thus messages are not received in time, causing
retransmissions (ACKs to be resent).
SOLUTION:
#1 Reduce contention and turn 'connections' from HashMap into ConcurrentHashMap
#2 Break 'connections' into a send-table and receive-table: sends and acks access
the send-table, receives the receive-table
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