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From "Eric Evans (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-272) Enhance how metrics are exposed
Date Mon, 06 Jul 2009 22:01:15 GMT


Eric Evans commented on CASSANDRA-272:

I have a couple of concerns about the organization/layout of instrumentation here.

1. I'm not sure it makes sense to have per-CF statistics reported on the CFMbean and then
aggregated/averaged on a TableMbean as well. Pretty much any monitoring application that I
can think of would collect on the individual CF-specific values, at which point doing the
math is straightforward. In short, I'm concerned this TableMbean will just be confusing if
all it contains is information that can be derived elsewhere.

2. At first, I liked what you did here in reorganizing the individual CFSs under ColumnFamilyStores
as opposed to object names formatted to include the tablename. Then I got to thinking about
what this will look like under generic JMX tools like jconsole, if for example there are different
tables that have identically named CFs. Thoughts?

Also, with respect to NodeProbe. When I originally put this together, I was thinking in terms
of the class being useful in creating a real monitoring system. That's why there are instance
variables for memory, runtime, and the storage service proxies/mbeans, even though no single
command uses them all. I don't know if that really makes sense to keep doing as we add more
and more instrumentation (especially if a monitoring system is vaporware, and the only use
is via main()). Thoughts on this?

> Enhance how metrics are exposed
> -------------------------------
>                 Key: CASSANDRA-272
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>    Affects Versions: 0.3
>            Reporter: Sammy Yu
>            Assignee: Sammy Yu
>            Priority: Minor
>             Fix For: 0.3
>         Attachments: 0001--Work-for-cassandra-272.patch, 0002--Work-for-cassandra-272.patch
> Had discussion on IRC about the metric interfaces that are used in the code today.  There
are two sets one using IAnalyticsSource to send data to Gangalia and another set of interface
using JMX MBeans (ie, ColumnStoreFamily).  
> Since FB is not using Gangalia anymore and it looks like the other VMAnalyticsSource
is already available via JMX, we should prefer to expose metrics through JMX.  I will add
a new TableMBean which exposes the metrics in  DBAnalyticsSource.

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