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https://issues.apache.org/jira/browse/CASSANDRA-11116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15134793#comment-15134793
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Jason Brown edited comment on CASSANDRA-11116 at 2/5/16 7:29 PM:
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[~aweisberg] does adding {{volatile}} have an affect on publication when
changes internal to {{scheduledGossipTask}} occur, or only when the
{{scheduledGossipTask}} variable itself is updated? In {{Gossiper#stop}}, we
call {{scheduledGossipTask.cancel(false);}}.
Either way, we need the {{volatile}} when (re-)starting Gossip
({{Gossiper#start()}}), but I'm not sure we solve the problem on stopping
gossip.
was (Author: jasobrown):
[~aweisberg] does adding {{volatile}} have an affect on publication when
changes internal to {{scheduledGossipTask}} occur, or only when the
{{scheduledGossipTask}} variable itself is updated? In {{Gossiper#stop}}, we
call {{scheduledGossipTask.cancel(false);}}.
Either way, we need the {{volatile}} when (re-)starting Gossip
({{Gossiper#start()}}, but I'm not sure we solve the problem on stopping gossip.
> Gossiper#isEnabled is not thread safe
> -------------------------------------
>
> Key: CASSANDRA-11116
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11116
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Sergio Bossa
> Assignee: Ariel Weisberg
> Priority: Critical
>
> {{Gossiper#isEnabled()}} relies on the presence of {{scheduledGossipTask}},
> which is not final nor volatile. As a consequence, when such method is called
> on a different thread, i.e. the gossip stage thread, it is sometimes detected
> as not enabled, causing particularly obscure failures.
> This is shown by the following logs. First the gossiper is started:
> {noformat}
> 1 TRACE [Thread-29] 2016-02-03 19:21:31,232 Gossiper.java (line 1310) gossip
> started with generation 1454527291
> {noformat}
> Then the same node misses a gossip message because the gossiper is seen as
> disabled:
> {noformat}
> 1 TRACE [GossipStage:1] 2016-02-03 19:21:32,016
> GossipDigestSynVerbHandler.java (line 44) Ignoring GossipDigestSynMessage
> because gossip is disabled
> {noformat}
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