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- type = stream-state-metrics,
- thread-id = [thread ID],
- task-id = [task ID]
- rocksdb-state-id = [store ID] for key-value stores
- rocksdb-session-state-id = [store ID] for session stores
- rocksdb-window-state-id = [store ID] for window stores
The following metrics will be exposed in the Kafka Streams' metrics
- bytes-written-rate [bytes/s]
- bytes-written-total [bytes]
- bytes-read-rate [bytes/s]
- bytes-read-total [bytes]
- memtable-bytes-flushed-rate [bytes/s]
- memtable-bytes-flushed-total [bytes]
- memtable-flush-time-(avg|min|max) [ms]
- memtable-hit-rate
- block-cache-data-hit-rate
- block-cache-index-hit-rate
- block-cache-filter-hit-rate
- bytes-read-compaction-rate [bytes/s]
- bytes-written-compaction-rate [bytes/s]
- compaction-time-(avg|min|max) [ms]
- write-stall-duration-(avg|total) [ms]
- num-open-files
- num-file-errors-total
...
Analogously to bytes-written-(rate|total), these metrics measure the bytes read from a RocksDB instance. The metrics show the read load on a RockDB instance.
memtable-bytes-flushed-(rate|total) and memtable-flush-time-(avg|min|max)
When data is put into RocksDB, the data is written into a in-memory tree data structure called memtable. When the memtable is almost full, data in the memtable is flushed to disk by a background process. Metrics bytes-flushed-(rate|total) measure the average throughput of flushes and the total amount of bytes written to disk. Metrics flush-time-(avg|min|max) measure the processing time of flushes.
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