I upgraded from logstash 6.2.2 to 6.3.2 (deleting queue directories). After first start, events were received but none showed emitted, queue files were growing in size. I couldn't find any errors, After restart, it looks OK.
The longer flat line is the first good start of 6.3.2. (the little blip is where it didn't run as root for port 514, my systemd error)
I have several logstash instances behind a network load balancer or in a beats list.
Is there any way to monitor the queue size in logstash?