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https://issues.apache.org/jira/browse/CASSANDRA-13052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15795285#comment-15795285
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Stefan Podkowinski commented on CASSANDRA-13052:
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{quote}
We soon notice heavy streaming and according to the logs the number of ranges
streamed was in thousands.
{quote}
[~cmposto], I'm currently a bit confused while trying to evaluate the actual
effect of this behaviour. I was first a bit concerned about either having
ranges streamed that shouldn't be repaired or to send identical ranges thousand
of times. But I've come to the conclusion that none of this should happen, as
{{StreamSession.addTransferRanges()}} should normalize all redundant ranges
into a singe range, before starting to stream any files. Can you further
describe how this bug resulted into "heavy streaming" on your cluster? What was
is that you noticed before further looking into this issue?
> Repair process is violating the start/end token limits for small ranges
> -----------------------------------------------------------------------
>
> Key: CASSANDRA-13052
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13052
> Project: Cassandra
> Issue Type: Bug
> Components: Streaming and Messaging
> Environment: We tried this in 2.0.14 and 3.9, same bug.
> Reporter: Cristian P
> Assignee: Stefan Podkowinski
> Attachments: ccm_reproduce-13052.txt, system-dev-debug-13052.log
>
>
> We tried to do a single token repair by providing 2 consecutive token values
> for a large column family. We soon notice heavy streaming and according to
> the logs the number of ranges streamed was in thousands.
> After investigation we found a bug in the two partitioner classes we use
> (RandomPartitioner and Murmur3Partitioner).
> The midpoint method used by MerkleTree.differenceHelper method to find ranges
> with differences for streaming returns abnormal values (way out of the
> initial range requested for repair) if the repair requested range is small (I
> expect smaller than 2^15).
> Here is the simple code to reproduce the bug for Murmur3Partitioner:
> Token left = new Murmur3Partitioner.LongToken(123456789L);
> Token right = new Murmur3Partitioner.LongToken(123456789L);
> IPartitioner partitioner = new Murmur3Partitioner();
> Token midpoint = partitioner.midpoint(left, right);
> System.out.println("Murmur3: [ " + left.getToken() + " : " +
> midpoint.getToken() + " : " + right.getToken() + " ]");
> The output is:
> Murmur3: [ 123456789 : -9223372036731319019 : 123456789 ]
> Note that the midpoint token is nowhere near the suggested repair range. This
> will happen if during the parsing of the tree (in
> MerkleTree.differenceHelper) in search for differences there isn't enough
> tokens for the split and the subrange becomes 0 (left.token=right.token) as
> in the above test.
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