# How to use LruRedux cache in ruby filter
**URL:** https://discuss.elastic.co/t/how-to-use-lruredux-cache-in-ruby-filter/347893
**Category:** Elasticsearch
**Created:** [November 24, 2023, 2:44am UTC](https://discuss.elastic.co/t/how-to-use-lruredux-cache-in-ruby-filter/347893 "2023-11-24T02:44:03Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Chen\_Wei](https://discuss.elastic.co/u/Chen_Wei)
#### Post date: [November 24, 2023, 2:44am UTC](https://discuss.elastic.co/t/how-to-use-lruredux-cache-in-ruby-filter/347893/1 "2023-11-24T02:44:03Z")
Somehow we have some logs having duplicated events, we want to dedup the events using fingerprint and LRU cache in the logstash pipeline, So I write a ruby file
```auto
require "lru_redux"
def register(params)
limit = params["size"]
@processedEvents = LruRedux::TTL::ThreadSafeCache.new(limit, 3600 )
end
def filter(event)
return [event]
end
```
When i try to load the script and test, logstash report :
he given configuration is invalid. Reason: Unable to configure plugins: (ScriptError) Error during load of '/Users/i337803/Workspaces/mcap/email-loganalyzer/email-loganalyzer-logstash/src/main/logstash/scripts/dedup.rb': #\
I don't see the operator '\<' in my file, What does this error complain about, I have no idea?
BTW, I see the Lru is already installed in the official Logstash package.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [December 22, 2023, 2:44am UTC](https://discuss.elastic.co/t/how-to-use-lruredux-cache-in-ruby-filter/347893/2 "2023-12-22T02:44:39Z")
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