Hi,
I would like to work on introducing an explicit support in Maven Core for
recording "metrics".
As far as I know (and I have still limited knowledge about the internals)
you can write an "extension" and you can intercept main lifecycle events,
and using these hooks you can try to record metrics.
But my proposal is from another point of view and I want to go deeper.
We are adding caches, making refactors....all good things, but we should
have a way to track how Maven is behaving in a measurable manner.
Usually in order to capture realtime metrics you are using some Metrics
framework, like Prometheus, Dropwizards....and you attach your process to a
metrics database and capture all of the values.
Then you can process all of the data, realtime and/or offline, you can
create dashboards, you can also fine tune your configuration or change your
code.
These frameworks deal with time series created by capturing Counters,
Summaries, Gauges.
I would like to introduce an API to be used by Maven Core and by Plugin to
expose internal metrics, like:
- internal caches size
- memory usage
- disk reads/writes
- network traffic
- any kind of specific metric for plugins (like "number of tests executed",
"number of files sent to javac...")
- .... all of the usual stuff you track in order to understand wha's going
on
I am saying a Maven Metrics API because we must not stick to a single
"provider" (say "DropWizard"), it will be a bad choice in the long term.
The API will expose to Maven Core and to plugins a way to get access to
Metrics and report useful values.
@InjectMe
MetricsProvider metrics;
metrics.getCounter("javacFiles").add(....)
metrics.getSummary("downloadTime").add(....)
I don't want to go down into details as this is only a preliminary email
but in my view we could let the user attach an "implementation" just by
dropping in an "extension", in order not to ship with Maven Core a lot of
third party dependencies.
I have some "production" experience with this topic (actually I did
something like that in my company and in ZooKeeper project) so I will be
happy to prepare and share a design document.
With this work we will open up the way to knowing how a Maven build works,
with the 'time dimension', on the local machine of the developer but even
on CI servers.
Any comment is very welcome
Regards
Enrico
