A small ruby script which basically spams an MQTT broker.

gistfile1.rb

require 'mqtt/client'

mqtt = MQTT::Client.new('10.25.2.4')

loop do
  
  mqtt.connect do |c|
    c.publish('test/foo/bar','this is a test message #{Time.now}')
    puts "published a msg"
  
    sleep 0.05
  end

end

Hmm, I still have no clue as to the problem. About the block/connection/disconnection issue though, as I understand it, you are right. The block passed into the connect method is executed after a connection, then it is disconnected. The client (in my case, the mqtt variable) can be reused though, as you just have it connect again.

If you watch the broker's log output, it does definitely connect, do its thing and disconnect. However I too saw what you're describing when stopping the broker. I assume that is some sort of cleanup process in the broker (removing the record of previous clients perhaps?)

But both my experience and yours seem to point at the gem not being that reliable. Looking at the code myself (I'm no expect, but...) it does look like perhaps things are somewhat optimistic - if it doesn't get what it expects, when it expects it, all hell breaks loose.