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https://issues.apache.org/jira/browse/CASSANDRA-10887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15065048#comment-15065048
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sankalp kohli commented on CASSANDRA-10887:
-------------------------------------------
I have added a patch along with many unit tests. Looks like the issue with
moves is there since the feature was added in CASSANDRA-1427.
This patch fixes the following issues
1) It will add the correct endpoints to the pending range not just the endpoint
which is moving.
2) It will remove the ranges which the endpoint is already getting. Eg: If an
endpoint is getting range 10-20 before the move and needs range say 15-20 after
the move, it will only add 15-20.
I think 2) will solve the problem of duplicate endpoints in pending endpoint
and natural endpoint. Thought I have not tested this part.
Most of the patch is unit tests which simulate many types of moves. We should
see if there is any case of move which is missing.
PS: I have not tested this patch apart from the unit test :)
> Pending range calculator gives wrong pending ranges for moves
> -------------------------------------------------------------
>
> Key: CASSANDRA-10887
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10887
> Project: Cassandra
> Issue Type: Bug
> Components: Coordination
> Reporter: Richard Low
> Assignee: sankalp kohli
> Priority: Critical
> Attachments: CASSANDRA-10887.diff
>
>
> My understanding is the PendingRangeCalculator is meant to calculate who
> should receive extra writes during range movements. However, it adds the
> wrong ranges for moves. An extreme example of this can be seen in the
> following reproduction. Create a 5 node cluster (I did this on 2.0.16 and
> 2.2.4) and a keyspace RF=3 and a simple table. Then start moving a node and
> immediately kill -9 it. Now you see a node as down and moving in the ring.
> Try a quorum write for a partition that is stored on that node - it will fail
> with a timeout. Further, all CAS reads or writes fail immediately with
> unavailable exception because they attempt to include the moving node twice.
> This is likely to be the cause of CASSANDRA-10423.
> In my example I had this ring:
> 127.0.0.1 rack1 Up Normal 170.97 KB 20.00%
> -9223372036854775808
> 127.0.0.2 rack1 Up Normal 124.06 KB 20.00%
> -5534023222112865485
> 127.0.0.3 rack1 Down Moving 108.7 KB 40.00%
> 1844674407370955160
> 127.0.0.4 rack1 Up Normal 142.58 KB 0.00%
> 1844674407370955161
> 127.0.0.5 rack1 Up Normal 118.64 KB 20.00%
> 5534023222112865484
> Node 3 was moving to -1844674407370955160. I added logging to print the
> pending and natural endpoints. For ranges owned by node 3, node 3 appeared in
> pending and natural endpoints. The blockFor is increased to 3 so we’re
> effectively doing CL.ALL operations. This manifests as write timeouts and CAS
> unavailables when the node is down.
> The correct pending range for this scenario is node 1 is gaining the range
> (-1844674407370955160, 1844674407370955160). So node 1 should be added as a
> destination for writes and CAS for this range, not node 3.
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