[jira] [Commented] (CASSANDRA-17062) Expose Auth Caches metrics

["Aleksei Zotov (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-17062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17443143#comment-17443143 ] 

Aleksei Zotov commented on CASSANDRA-17062:
-------------------------------------------

[~samt] [~blerer] 

I've started working on this and mentioned a discrepancy between non-auth (key, row, counter, chunk) and auth caches. The non-auth caches are weighted (they do care about weight of a single entry) whereas the auth caches are non-weighted. Particularly it affects _Capacity_ and _Size_ attributes of the MBeans. For weighted caches they represent size of entries in bytes, for non-weighted caches they represent number of entries.

Current changes do not particularly handle this logical discrepancy (the only thing I've done is renaming of capacity_bytes -> capacity and size_bytes -> size in the corresponding VT). What can be actually done to make the logic a bit clearer:
 # Introduce "weighted" column to the VT and add corresponding notes to the documentation on how to treat capacity and size for weighted/non-weighted caches. But we can mention that without having the new column.
 # Make auth caches weighted. I feel it would make things even worse because it is not really required from logical standpoint (and it would be hard to precisely calculate used memory for auth caches).
 # Completely separate metrics for weighted and non-weighted caches. It is opposite to unification I supposed to achieve by this ticket. However, it should make things clear and precise.

Please, share your thoughts (maybe you have other ideas). I linked a draft PR for your reference.

> Expose Auth Caches metrics
> --------------------------
>
>                 Key: CASSANDRA-17062
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-17062
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Feature/Virtual Tables, Observability/Metrics, Tool/nodetool
>            Reporter: Aleksei Zotov
>            Assignee: Aleksei Zotov
>            Priority: Normal
>             Fix For: 4.x
>
>
> Unlike to other caches (row, key, counter), Auth Caches lack some monitoring capabilities. Here are a few particular changes to get this inequity fixed:
>  # Add auth caches to _system_views.caches_ VT
>  # Expose auth caches metrics via JMX
>  # Add auth caches details to _nodetool info_
>  



--
This message was sent by Atlassian Jira
(v8.20.1#820001)

---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@cassandra.apache.org
For additional commands, e-mail: commits-help@cassandra.apache.org