Re: JSON PMDA (was Re: [pcp] PCP JMX PMDA)

[Nathan Scott <nathans@xxxxxxxxxx>]

Hi guys,

----- Original Message -----
> [...]
> >> * metadata.json updates are not picked up during JSON PMDA lifetime
> > 
> > Yes, that is true. As far as I know, that's fairly standard for PMDAs,
> > especially python ones.
> 
> Ok, Nathan mentioned earlier that the Python PMDA API was extended to
> allow adding metrics dynamically so if metadata.json updates are not
> picked up then on the fly then perhaps he meant something else.

I was referring to all the work David did to allow metrics to be defined
dynamically for python PMDAs (i.e. such that add_metric() can be called
after the PMDA enters its run() routine ... see commit ddfdbf144982bb1).

I'm a little surprised its not more dynamic than it is.  MMV handles the
dynamic addition and removal of metrics, and I thought pmdajson did that
too - apologies, my mistake there (I'd assumed this would be needed/used
for the systemtap support?).  It is indeed relatively uncommon though as
David says, to have that level of flexibility in any PMDA.

cheers.

--
Nathan