[jira] [Created] (CASSANDRA-9640) Nodetool repair of very wide, large rows causes GC pressure and destabilization

["Constance Eustace (JIRA)" <ji...@apache.org>]

Constance Eustace created CASSANDRA-9640:
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             Summary: Nodetool repair of very wide, large rows causes GC pressure and destabilization
                 Key: CASSANDRA-9640
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9640
             Project: Cassandra
          Issue Type: New Feature
         Environment: AWS, ~8GB heap
            Reporter: Constance Eustace
            Priority: Minor


We've noticed our nodes becoming unstable with large, unrecoverable Old Gen GCs until OOM.

This appears to be around the time of repair, and the specific cause seems to be one of our report computation tables that involves possible very wide rows with 1TB of data in it. THis is an RF 3 table in a four-node cluster.

We truncate this occasionally, and we also had disabled this computation report for a bit and noticed better node stabiliy.

I wish I had more specifics. We are switching to an RF 1 table and do more proactive truncation of the table. 

When things calm down, we will attempt to replicate the issue and watch GC and other logs.

Any suggestion for things to look for/enable tracing on would be welcome.




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