metrics.gauge.LazyDelegatingGauge unknown type

Updated logstash and are still seeing the warning: constant ::Fixnum upon launching logstash anything to do clear this warning?

Downloading Packages:
logstash-7.6.0.rpm                                                                                                       | 158 MB     00:02     
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Updating   : 1:logstash-7.6.0-1.noarch                                                                       1/2 
warning: /etc/logstash/logstash.yml created as /etc/logstash/logstash.yml.rpmnew
Using provided startup.options file: /etc/logstash/startup.options
/usr/share/logstash/vendor/bundle/jruby/2.5.0/gems/pleaserun-0.0.30/lib/pleaserun/platform/base.rb:112: warning: constant ::Fixnum is deprecated
Successfully created system startup script for Logstash
  Cleanup    : 1:logstash-7.5.1-1.noarch                                                                        2/2 
  Verifying  : 1:logstash-7.6.0-1.noarch                                                                         1/2 
  Verifying  : 1:logstash-7.5.1-1.noarch                                                                         2/2 

Updated:
  logstash.noarch 1:7.6.0-1                                                                                                                                                                       

Complete!
Validating logstash-input-jmx
Installing logstash-input-jmx
Installation successful

And the warning of the gauge metric of unknown type in the log?

[2020-02-13T11:59:21,396][WARN ][logstash.config.source.multilocal] Ignoring the 'pipelines.yml' file because modules or command line options are specified
[2020-02-13T11:59:27,877][WARN ][logstash.outputs.elasticsearch][main] Restored connection to ES instance {:url=>"http://<redacted>:xxxxxx@es-mst1:9200/"}
[2020-02-13T11:59:27,941][WARN ][logstash.outputs.elasticsearch][main] Detected a 6.x and above cluster: the `type` event field won't be used to determine the document _type {:es_version=>7}
[2020-02-13T11:59:27,980][WARN ][logstash.outputs.elasticsearch][main] Restored connection to ES instance {:url=>"http://<redacted>:xxxxxx@es-mst2:9200/"}
[2020-02-13T11:59:28,017][WARN ][logstash.outputs.elasticsearch][main] Restored connection to ES instance {:url=>"http://<redacted>:xxxxxx@es-mst3:9200/"}
[2020-02-13T11:59:28,418][WARN ][org.logstash.instrument.metrics.gauge.LazyDelegatingGauge][main] A gauge metric of an unknown type (org.jruby.specialized.RubyArrayOneObject) has been create for key: cluster_uuids. This may result in invalid serialization.  It is recommended to log an issue to the responsible developer/development team.

TIA

I believe that is normal and you can ignore it.

Have been for long, only thought I would mention it as dev team recommends notifying them :slight_smile:

Any clue about the constant ::Fixnum warning?

A known issue on third-party (ish) software.

Right, as I read this ticket is still open and thus no fix to bundle with logstash yet :frowning:
Assume time will resolve this... haven't seen any issue due to this though with our logstash processing.