[jira] [Created] (CASSANDRA-10789) Allow DBAs to kill individual client sessions without bouncing JVM

["Wei Deng (JIRA)" <ji...@apache.org>]

Wei Deng created CASSANDRA-10789:
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             Summary: Allow DBAs to kill individual client sessions without bouncing JVM
                 Key: CASSANDRA-10789
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10789
             Project: Cassandra
          Issue Type: Improvement
          Components: Coordination
            Reporter: Wei Deng


In production, there could be hundreds of clients connected to a Cassandra cluster (maybe even from different applications), and if they use DataStax Java Driver, each client will establish at least one TCP connection to a Cassandra server (see https://datastax.github.io/java-driver/2.1.9/features/pooling/). This is all normal and at any given time, you can indeed see hundreds of ESTABLISHED connections to port 9042 on a C* server (from netstat -na). The problem is that sometimes when a C* cluster is under heavy load, when the DBA identifies some client session that sends abusive amount of traffic to the C* server and would like to stop it, they would like a lightweight approach rather than shutting down the JVM or rolling restart the whole cluster to kill all hundreds of connections. If the DBA had root privilege, they would have been able to do something at the OS network level to achieve the same goal but oftentimes enterprise DBA role is separate from OS sysadmin role, so the DBAs usually don't have that privilege.

This is especially helpful when you have a multi-tenant C* cluster and you want to have the impact for handling such client to be minimal to the other applications. This feature (killing individual session) seems to be a common feature in other databases (regardless of whether the client has some reconnect logic or not). It could be implemented as a JMX MBean method and exposed through nodetool to the DBAs.



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