bbejeck opened a new pull request, #19956:
URL: https://github.com/apache/kafka/pull/19956

   PR #16922 is part of 
[KIP-892](https://cwiki.apache.org/confluence/display/KAFKA/KIP-892%3A+Transactional+Semantics+for+StateStores)
 to enable transactional semantics for state stores.  In particular, on 
starting a Kafka Streams instance, if it has pre-existing state, the state 
stores are initialized on the main thread.  Part of this initialization 
registers the stateful metrics with the JMX thread-id tag of `main`.  This 
breaks the KIP-1076 implementation where need to register metrics with 
thread-id tags of `xxxStreamThread-N`.  This is necessary due to the fact that 
the `StreamsMetric` is a singleton shared by all `StreamThread` instances, so 
we need to make sure only add metrics for the current `StreamThread` otherwise 
duplicate metrics are registered.  By registering metrics on the main thread, 
state metrics `size-all-mem-tables`, `estimate-num-keys`, and 
`block-cache-useage` get omitted. This PR reverts the changes until a fix is 
implemented, allowing the individual  `Stream
 Thread`s to register the metrics.


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