[GitHub] [pulsar] lhotari opened a new pull request #9735: [Metrics] Reduce CPU consumption of metrics creation

[GitBox]

lhotari opened a new pull request #9735:
URL: https://github.com/apache/pulsar/pull/9735


   ### Motivation
   
   `String.format` is consuming most CPU when generating metrics:
   
![image](https://user-images.githubusercontent.com/66864/109286532-05226880-782b-11eb-9074-a578b1a83284.png)
   ([Flamegraph from Pulsar 
user](https://apache-pulsar.slack.com/archives/C5Z4T36F7/p1614331656110600?thread_ts=1614293057.103600&cid=C5Z4T36F7))
   
   ### Modifications
   
   Replace the usage of `String.format` with usage of `StringBuilder` and 
thread local cached `DecimalFormat`.


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