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Re: [pcp] JSON PMDA

To: David Smith <dsmith@xxxxxxxxxx>
Subject: Re: [pcp] JSON PMDA
From: Nathan Scott <nathans@xxxxxxxxxx>
Date: Thu, 7 May 2015 19:35:10 -0400 (EDT)
Cc: pcp <pcp@xxxxxxxxxxx>
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Reply-to: Nathan Scott <nathans@xxxxxxxxxx>
Thread-index: 6Hu36q+kcJnQWFTSNSBc/dNYqBnDmw==
Thread-topic: JSON PMDA

----- Original Message -----
> >> [...]
> 
> This patch is cleaned up a good bit. I fixed the above items and made
> several changes to pmda.py.
> 
> I've got a question about the "exports" file, which I've never messed
> with before. Should I have put the new function at the end of the list?
> Do I need to define a new library version?

Yep - a PCP_PMDA_3.5 will be needed.

> I've got a "philosophy" question about the pmda itself. Originally, each
> array had its own indom cache. For this new version, I've switched to
> one indom cache per JSON source (each JSON source is also in its own
> cluster). I think I can see a way to switch back to the original method
> (by adding another cache that maps cache numbers back to arrays), but I
> wasn't sure which way was more "correct".

>From a PCP philosophy point of view an indom represents a set-of-somethings
from one PMDA (e.g. set of disks, set of CPUs) - so, in this case, if more
than one JSON-defined metric has values expanded across a set-of-somethings
those metrics should use the *same* indom (i.e. same serial#).

Provided that can be represented, I guess it doesn't matter how things are
managed internally in the PMDA.

cheers.

--
Nathan

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