Thanks Ben for your comments!
Indeed, there is an issue about failover regarding the polling thread.
To that extent, pushing metrics to a sink would be better. To make this
push runner agnostic, doing the code in the runner-common part of beam
would be good. Maybe in the runner API like JB suggests.
IMHO It would be good to change the POC JB and I have started to that
direction.
Question is: what is the proper extension point to add the push?
Somewhere like org.apache.beam.runners.core.metrics.MetricsContainerImpl ?
Best
Etienne
Le 27/11/2017 à 18:26, Jean-Baptiste Onofré a écrit :
Yeah, I think that something in the runner makes sense.
The only drawback is that it would require some enforcement on the
runners and change on all runners.
If it could be part of the Runner API, that would help I think.
The idea of the thread poller was more in PoC way. Only the
polling/sending should be part of the runner. Marshaller and Sink
should stay as interface and implemented. It would give us more
flexibility.
Regards
JB
On 11/27/2017 06:17 PM, Ben Chambers wrote:
I think discussing a runner agnostic way of configuring how metrics are
extracted is a great idea -- thanks for bringing it up Etienne!
Using a thread that polls the pipeline result relies on the program that
created and submitted the pipeline continuing to run (eg., no machine
faults, network problems, etc.). For many applications, this isn't a
good
model (a Streaming pipeline may run for weeks, a Batch pipeline may be
automatically run every hour, etc.).
Etienne's proposal of having something the runner pushes metrics too has
the benefit of running in the same cluster as the pipeline, thus
having the
same reliability benefits.
As noted, it would require runners to ensure that metrics were pushed
into
the extractor but from there it would allow a general configuration
of how
metrics are extracted from the pipeline and exposed to some external
services.
Providing something that the runners could push metrics into and have
them
automatically exported seems like it would have several benefits:
1. It would provide a single way to configure how metrics are
actually
exported.
2. It would allow the runners to ensure it was reliably executed.
3. It would allow the runner to report system metrics directly
(eg., if a
runner wanted to report the watermark, it could push that in directly).
-- Ben
On Mon, Nov 27, 2017 at 9:06 AM Jean-Baptiste Onofré <[email protected]>
wrote:
Hi all,
Etienne forgot to mention that we started a PoC about that.
What I started is to wrap the Pipeline creation to include a thread
that
polls
periodically the metrics in the pipeline result (it's what I
proposed when
I
compared with Karaf Decanter some time ago).
Then, this thread marshalls the collected metrics and send to a
sink. At
the
end, it means that the harvested metrics data will be store in a
backend
(for
instance elasticsearch).
The pro of this approach is that it doesn't require any change in the
core, it's
up to the user to use the PipelineWithMetric wrapper.
The cons is that the user needs to explicitly use the
PipelineWithMetric
wrapper.
IMHO, it's good enough as user can decide to poll metrics for some
pipelines and
not for others.
Regards
JB
On 11/27/2017 04:56 PM, Etienne Chauchot wrote:
Hi all,
I came by this ticket https://issues.apache.org/jira/browse/BEAM-2456.
I know
that the metrics subject has already been discussed a lot, but I would
like to
revive the discussion.
The aim in this ticket is to avoid relying on the runner to provide
the
metrics
because they don't have all the same capabilities towards metrics. The
idea in
the ticket is to still use beam metrics API (and not others like
codahale as it
has been discussed some time ago) and provide a way to extract the
metrics with
a polling thread that would be forked by a PipelineWithMetrics (so,
almost
invisible to the end user) and then to push to a sink (such as a Http
rest sink
for example or Graphite sink or anything else...). Nevertheless, a
polling
thread might not work for all the runners because some might not
make the
metrics available before the end of the pipeline. Also, forking a
thread
would
be a bit unconventional, so it could be provided as a beam sdk
extension.
Another way, to avoid polling, would be to push metrics values to a
sink
when
they are updated but I don't know if it is feasible in a runner
independent way.
WDYT about the ideas in this ticket?
Best,
Etienne
--
Jean-Baptiste Onofré
[email protected]
http://blog.nanthrax.net
Talend - http://www.talend.com
