[jira] [Created] (CASSANDRA-7402) limit the on heap memory avallible to requests

["T Jake Luciani (JIRA)" <ji...@apache.org>]

T Jake Luciani created CASSANDRA-7402:
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             Summary: limit the on heap memory avallible to requests
                 Key: CASSANDRA-7402
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7402
             Project: Cassandra
          Issue Type: Improvement
            Reporter: T Jake Luciani
             Fix For: 3.0


When running a production cluster one common operational issue is quantifying GC pauses caused by ongoing requests.

Since different queries return varying amount of data you can easily get your self into a situation where you Stop the world from a couple of bad actors in the system.  Or more likely the aggregate garbage generated on a single node across all in flight requests causes a GC.

We should be able to set a limit on the max heap we can allocate to all outstanding requests and track the garbage per requests to stop this from happening.  It should increase a single nodes availability substantially.

In the yaml this would be

{code}
total_request_memory_space_mb: 400
{code}

It would also be nice to have either a log of queries which generate the most garbage so operators can track this.  Also a histogram.




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