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https://issues.apache.org/jira/browse/CASSANDRA-17342?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17490314#comment-17490314
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Paul Chandler commented on CASSANDRA-17342:
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Hi [~marcuse] I have finally fixed the email address on my commits (I've been
held back by too many production issues). Not sure if that was the right thing
to do now, as there are later changes in your repository.
Not sure if you were waiting for me, or what the next step is now.
> Performance problem for node restart with incremental range repairs
> -------------------------------------------------------------------
>
> Key: CASSANDRA-17342
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17342
> Project: Cassandra
> Issue Type: Bug
> Components: Consistency/Repair
> Reporter: Paul Chandler
> Assignee: Paul Chandler
> Priority: Normal
> Fix For: 4.0.x
>
> Attachments: BulkRepairStateTest.java,
> IncrementalRepairStartupTest.java, LocalSessions.java, RepairedState.java
>
>
> There is a performance problem when restarting cassandra for clusters doing
> incremental repairs with range repairs.
> We have clusters with 16 vnodes per node, and are splitting each vnode into
> 100 ranges, this causes a node to take over 30 minutes to process the data
> stored in the system.repairs table before the node can restart. Even when we
> reduce this to 10 ranges per vnode this still takes 2 minutes to process. The
> cluster has 22 keyspaces and a rf of 3, this creates around 8100 records in
> the system.repairs table.
>
> The problem seems to occur in the
> org.apache.cassandra.repair.consistent.RepairState class where the add method
> re processes the complete list, including sorting, every time a new Range is
> added. This leads is an exponential growth in processing time, this is
> demonstrated in the attached unit test.
>
> I have created a change, that collects the data read in from the
> system.repairs table, in the
> org.apache.cassandra.repair.consistent.LocalSessions class, before processing
> it as a group at the end, this reduces the processing time to a couple of
> seconds even for the 100 range version.
>
> This is my first attempt at changing the cassandra code, so I am in need of a
> mentor to help me with the process, and validate what I have done.
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