[jira] [Created] (CASSANDRA-12146) Use dedicated executor for sending JMX notifications

["Stefan Podkowinski (JIRA)" <ji...@apache.org>]

Stefan Podkowinski created CASSANDRA-12146:
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             Summary: Use dedicated executor for sending JMX notifications
                 Key: CASSANDRA-12146
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12146
             Project: Cassandra
          Issue Type: Bug
            Reporter: Stefan Podkowinski
            Assignee: Stefan Podkowinski


I'm currently looking into an issue with our repair process where we can notice a significant delay at the end of the repair task and before nodetool is actually terminating. At the same time JMX NOTIF_LOST errors are reported in nodetool during most repair runs.

Currently {{StorageService.repairAsync(keyspace, options)}} is called through JMX, which will start a new thread executing RepairRunnable using the provided options. StorageService itself implements NotificationBroadcasterSupport and will send JMX progress notifications emitted from RepairRunnable (or during bootstrap). If you take a closer look at {{RepairRunnable}}, {{JMXProgressSupport}} and {{StorageService/NotificationBroadcasterSupport.sendNotification}} you'll notice that this all happens within the calling thread, i.e. RepairRunnable. Given the lost notifications and all kind of potential networking related issues, I'm not really comfortable having the repair coordinator thread running in the JMX stack. Fortunately NotificationBroadcasterSupport accepts a custom executor as constructor argument. See attached patched.



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