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https://issues.apache.org/jira/browse/CASSANDRA-12653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15878461#comment-15878461
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Joel Knighton commented on CASSANDRA-12653:
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I think I can answer these - feel free to correct me, [[email protected]]
In order,
* Presently, the tests depend on the mock MessagingService, which was added in
[CASSANDRA-12016] to 3.10+. We'd new tests for 2.2/3.0+, which is desirable,
but I have no great ideas how to do it other than fiddly byteman tests.
* I agree with this. Stefan and I discussed it on the first pass of review, and
I wouldn't mind eliminating that check altogether and making it a boolean.
OTOH, it's cheap to check deserialization time and excludes the messages that
were deserialized prior to the check. OTOH, there's no meaningful distinction
in correctness-preserving behaviors between that and arbitrarily delayed gossip
messages, and we need to handle the latter correctly anyway. I'm most concerned
about this check giving future readers false hope :).
* It also seems to be me that it doesn't presently need to be synchronized.
That said, I assumed it was a defensive choice because the internals are
definitely not safe to call on multiple threads, and someone may make that
mistake in the future.
> In-flight shadow round requests
> -------------------------------
>
> Key: CASSANDRA-12653
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12653
> Project: Cassandra
> Issue Type: Bug
> Components: Distributed Metadata
> Reporter: Stefan Podkowinski
> Assignee: Stefan Podkowinski
> Priority: Minor
> Fix For: 2.2.x, 3.0.x, 3.11.x, 4.x
>
>
> Bootstrapping or replacing a node in the cluster requires to gather and check
> some host IDs or tokens by doing a gossip "shadow round" once before joining
> the cluster. This is done by sending a gossip SYN to all seeds until we
> receive a response with the cluster state, from where we can move on in the
> bootstrap process. Receiving a response will call the shadow round done and
> calls {{Gossiper.resetEndpointStateMap}} for cleaning up the received state
> again.
> The issue here is that at this point there might be other in-flight requests
> and it's very likely that shadow round responses from other seeds will be
> received afterwards, while the current state of the bootstrap process doesn't
> expect this to happen (e.g. gossiper may or may not be enabled).
> One side effect will be that MigrationTasks are spawned for each shadow round
> reply except the first. Tasks might or might not execute based on whether at
> execution time {{Gossiper.resetEndpointStateMap}} had been called, which
> effects the outcome of {{FailureDetector.instance.isAlive(endpoint))}} at
> start of the task. You'll see error log messages such as follows when this
> happend:
> {noformat}
> INFO [SharedPool-Worker-1] 2016-09-08 08:36:39,255 Gossiper.java:993 -
> InetAddress /xx.xx.xx.xx is now UP
> ERROR [MigrationStage:1] 2016-09-08 08:36:39,255 FailureDetector.java:223
> - unknown endpoint /xx.xx.xx.xx
> {noformat}
> Although is isn't pretty, I currently don't see any serious harm from this,
> but it would be good to get a second opinion (feel free to close as "wont
> fix").
> /cc [~Stefania] [~thobbs]
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