[root@app101 ~]# /opt/logstash/bin/logstash-plugin update logstash-filter-throttle
You are updating logstash-filter-throttle to a new version 4.0.1, which may not be compatible with 2.0.4. are you sure you want to proceed (Y/N)?
y
Updating logstash-filter-throttle
No plugin updated
[root@app101 ~]# /opt/logstash/bin/logstash --version
logstash 2.3.4
From https://www.elastic.co/guide/en/logstash/current/plugins-filters-throttle.html, the throttle filter plugin v4.0.1 should be compatible with logstash 2.3.4