On Wed, Jan 28, 2009 at 06:09:48AM -0800, Gilad Raphaelli wrote:
>
> I think this is a well thought out email and I'm a little surprised at
> the lack of response to it. Is it because no one is actually using
> the gmond python module interface and hasn't had to make these types
> of decisions? I don't have a single gmetric script/module that only
> collects one metric and have used both the mutli-threaded collector
> approach and the single-thread hopeful/naive approach (having written
> the mysql metric module you mention). I agree that the multi-threaded
> design seems less prone to problems but in practice I haven't had any
> problems either way. That being said, I will be trying some of your
> suggestions or moving to threads for that mysql module when time
> permits.
You could also modify gmond to run each plugin in a new thread, no sure
if it is easy/possible though since I haven't looked at that part of the
code yet.
> My frustration with the gmond python module interface is that it's not
> actually a complete replacement for gmetric scripts as I use them.
> Needing to know all of the metrics that a module will report before
> runtime makes for a lot of upfront work creating .pyconf files and
> doesn't allow for adding new metrics without restarting gmond. Being
> able to deploy one gmetric script that conditionally reports gmetrics
> based on what's running/hardware installed/etc on a box is a big
> advantage for a gmetric script over conditionally generating pyconf
> files and then still having to conditionally collect metrics in the
> actual gmond module. I expect most users just stick with the gmetric
> script in this case and handle scheduling themselves?
I agree here, my suggestion in the "Wildcard Configuration" was to add a
metric_autoconf function in the plugin and get gmond to use that to get
the collection_group from there. In any case for the modules that I
develop I call this function from main so I can do python module.py -t >
module.pyconf with a similar effect.
This doesn't solve all problems though, I would like to be able to just
start mysql in a host or add a new disk for example and have metrics for
them without touching the configuration at all. Maybe extending the
configuration so in a .pyconf you can write something like
collection_group {
autoconf = 300
}
to have gmond interogate the plugin every 5 mins to get a new collection
group will be enough, I need to think about it a bit more...
Kostas
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