How do we know logstash is reading from dead letter queue or not

Hi, I have added a input pipeline to read from dead queue then i restart the logstash and there is no error in logs but don't know if it is reading from dead queue or not. by the way there is no change in the size of dead queues.

Here is beats input conf

input {
beats {
port => 5044
ssl => false
}
dead_letter_queue {
path => "/var/lib/logstash/dead_letter_queue"
commit_offsets => true
pipeline_id => "main"
}
}

Please help :frowning: