Logstash does not reconnect when DB2 "SqlNonTransientConnectionException" is raised

[edmocosta]

This problem is caused when a connection gets closed by DB2 (idle sessions, workload rules, network issues, etc.)
Logstash should gracefully recover from those errors, discarding the stale connection and reconnecting the client. Instead, the plugin hangs trying to reuse the closed connection.

This issue probably started after changed the connection pattern to pooling (PR). As a workaround, we can enable the jdbc_validate_connection and set the jdbc_validation_timeout to a smaller interval value compared to the schedule option, E.g:

....
schedule => "*/5 * * * *" #5 minutes
jdbc_validate_connection => true
jdbc_validation_timeout => 270 #4.5 minutes

The plugin documentation should also include a note, instructing that the jdbc_validation_timeout should be smaller than the schedule period, otherwise the :validate_connection extension won't work.

The problem seems to be on the sequel gem adapters/jdbc#disconnect_error? method. This specific exception is not being wrapped into another exception, letting the :cause nil, not detecting the disconnection (jeremyevans/sequel#2083).