Logstash does not reconnect when Sybase raises "Connection is already closed"

[kaisecheng]

Similar issue to #143 , #152 , this time is Sybase. The upstream Sequel driver is affected by a connection issue as described in jeremyevans/sequel#2159 Sequel lib doesn't support Sybase, hence, the plugin needs special handling for Sybase to solve this issue.

def DB.disconnect_error?(exception, opts)
  super || exception.message =~ /Connection is already closed\.\z/
end

This problem is caused when a connection gets closed by Sybase (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/invalid connections.

[kaisecheng]

A workaround is enabling jdbc_validate_connection and set the jdbc_validation_timeout to a smaller interval value compared to the schedule option

for example a scheduler runs for every minute, jdbc_validation_timeout should be smaller than 60 seconds.

schedule => "* * * * *"
jdbc_validate_connection => true
jdbc_validation_timeout => 55 # 55 seconds