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From Chris Pettitt <cpett...@linkedin.com.INVALID>
Subject Re: [DISCUSS] SEP-2: ApplicationRunner Design
Date Thu, 27 Apr 2017 13:07:47 GMT
For #1, I doesn't have a hard requirement for any change from Samza. A very
nice to have would be to allow the input systems to be set up at the same
time as the rest of the StreamGraph. An even nicer to have would be to do
away with the callback based approach and treat graph building as a
library, a la Beam and Flink.

For the moment I've worked around the two pass requirement (once for
config, once for StreamGraph) by introducing an IR layer between Beam and
the Samza Fluent translation. The IR layer is convenient independent of
this problem because it makes it easier to switch between the Fluent and
low-level APIs.


For #4, if we had parity with StreamProcessor for lifecycle we'd be in
great shape. One additional issue with the status call that I may not have
mentioned is that it provides you no way to get at the cause of failure.
The StreamProcessor API does allow this via the callback.


Re. #2 and #3, I'm a big fan of getting rid of the extra configuration
indirection you currently have to jump through (this is also related to
system consumer configuration from #1. It makes it much easier to discover
what the configurable parameters are too, if we provide some programmatic
way to tweak them in the API - which can turn into config under the hood.

On Wed, Apr 26, 2017 at 9:20 PM, xinyu liu <xinyuliu.us@gmail.com> wrote:

> Let me give a shot to summarize the requirements for ApplicationRunner we
> have discussed so far:
>
> - Support environment for passing in user-defined objects (streams
> potentially) into ApplicationRunner (*Beam*)
>
> - Improve ease of use for ApplicationRunner to avoid complex configurations
> such as zkCoordinator, zkCoordinationService. (*Standalone*)
>
> - Clean up ApplicationRunner into a single interface (*Fluent*). We can
> have one or more implementations but it's hidden from the users.
>
> - Separate StreamGraph from environment so it can be serializable (*Beam,
> Yarn*)
>
> - Better life cycle management of application, including
> start/stop/stats (*Standalone,
> Beam*)
>
>
> One way to address 2 and 3 is to provide pre-packaged runner using static
> factory methods, and the return type will be the ApplicationRunner
> interface. So we can have:
>
>   ApplicationRunner runner = ApplicationRunner.zk() /
> ApplicationRunner.local()
> / ApplicationRunner.remote() / ApplicationRunner.test().
>
> Internally we will package the right configs and run-time environment with
> the runner. For example, ApplicationRunner.zk() will define all the configs
> needed for zk coordination.
>
> To support 1 and 4, can we pass in a lambda function in the runner, and
> then we can run the stream graph? Like the following:
>
>   ApplicationRunner.zk().env(config -> environment).run(streamGraph);
>
> Then we need a way to pass the environment into the StreamGraph. This can
> be done by either adding an extra parameter to each operator, or have a
> getEnv() function in the MessageStream, which seems to be pretty hacky.
>
> What do you think?
>
> Thanks,
> Xinyu
>
>
>
>
>
> On Sun, Apr 23, 2017 at 11:01 PM, Prateek Maheshwari <
> pmaheshwari@linkedin.com.invalid> wrote:
>
> > Thanks for putting this together Yi!
> >
> > I agree with Jake, it does seem like there are a few too many moving
> parts
> > here. That said, the problem being solved is pretty broad, so let me try
> to
> > summarize my current understanding of the requirements. Please correct me
> > if I'm wrong or missing something.
> >
> > ApplicationRunner and JobRunner first, ignoring test environment for the
> > moment.
> > ApplicationRunner:
> > 1. Create execution plan: Same in Standalone and Yarn
> > 2. Create intermediate streams: Same logic but different leader election
> > (ZK-based or pre-configured in standalone, AM in Yarn).
> > 3. Run jobs: In JVM in standalone. Submit to the cluster in Yarn.
> >
> > JobRunner:
> > 1. Run the StreamProcessors: Same process in Standalone & Test. Remote
> host
> > in Yarn.
> >
> > To get a single ApplicationRunner implementation, like Jake suggested, we
> > need to make leader election and JobRunner implementation pluggable.
> > There's still the question of whether ApplicationRunner#run API should be
> > blocking or non-blocking. It has to be non-blocking in YARN. We want it
> to
> > be blocking in standalone, but seems like the main reason is ease of use
> > when launched from main(). I'd prefer making it consitently non-blocking
> > instead, esp. since in embedded standalone mode (where the processor is
> > running in another container) a blocking API would not be user-friendly
> > either. If not, we can add both run and runBlocking.
> >
> > Coming to RuntimeEnvironment, which is the least clear to me so far:
> > 1. I don't think RuntimeEnvironment should be responsible for providing
> > StreamSpecs for streamIds - they can be obtained with a config/util
> class.
> > The StreamProcessor should only know about logical streamIds and the
> > streamId <-> actual stream mapping should happen within the
> > SystemProducer/Consumer/Admins provided by the RuntimeEnvironment.
> > 2. There's also other components that the user might be interested in
> > providing implementations of in embedded Standalone mode (i.e., not just
> in
> > tests) - MetricsRegistry and JMXServer come to mind.
> > 3. Most importantly, it's not clear to me who creates and manages the
> > RuntimeEnvironment. It seems like it should be the ApplicationRunner or
> the
> > user because of (2) above and because StreamManager also needs access to
> > SystemAdmins for creating intermediate streams which users might want to
> > mock. But it also needs to be passed down to the StreamProcessor - how
> > would this work on Yarn?
> >
> > I think we should figure out how to integrate RuntimeEnvironment with
> > ApplicationRunner before we can make a call on one vs. multiple
> > ApplicationRunner implementations. If we do keep LocalApplicationRunner
> and
> > RemoteApplication (and TestApplicationRunner) separate, agree with Jake
> > that we should remove the JobRunners and roll them up into the respective
> > ApplicationRunners.
> >
> > - Prateek
> >
> > On Thu, Apr 20, 2017 at 10:06 AM, Jacob Maes <jacob.maes@gmail.com>
> wrote:
> >
> > > Thanks for the SEP!
> > >
> > > +1 on introducing these new components
> > > -1 on the current definition of their roles (see Design feedback below)
> > >
> > > *Design*
> > >
> > >    - If LocalJobRunner and RemoteJobRunner handle the different methods
> > of
> > >    launching a Job, what additional value do the different types of
> > >    ApplicationRunner and RuntimeEnvironment provide? It seems like a
> red
> > > flag
> > >    that all 3 would need to change from environment to environment. It
> > >    indicates that they don't have proper modularity. The
> > > call-sequence-figures
> > >    support this; LocalApplicationRunner and RemoteApplicationRunner
> make
> > > the
> > >    same calls and the diagram only varies after jobRunner.start()
> > >    - As far as I can tell, the only difference between Local and Remote
> > >    ApplicationRunner is that one is blocking and the other is
> > > non-blocking. If
> > >    that's all they're for then either the names should be changed to
> > > reflect
> > >    this, or they should be combined into one ApplicationRunner and just
> > > expose
> > >    separate methods for run() and runBlocking()
> > >    - There isn't much detail on why the main() methods for Local/Remote
> > >    have such different implementations, how they receive the
> Application
> > >    (direct vs config), and concretely how the deployment scripts, if
> any,
> > >    should interact with them.
> > >
> > >
> > > *Style*
> > >
> > >    - nit: None of the 11 uses of the word "actual" in the doc are
> > > *actually*
> > >    needed. :-)
> > >    - nit: Colors of the runtime blocks in the diagrams are
> unconventional
> > >    and a little distracting. Reminds me of nai won bao. Now I'm hungry.
> > :-)
> > >    - Prefer the name "ExecutionEnvironment" over "RuntimeEnvironment".
> > The
> > >    term "execution environment" is used
> > >    - The code comparisons for the ApplicationRunners are not
> > apples-apples.
> > >    The local runner example is an application that USES the local
> runner.
> > > The
> > >    remote runner example is the just the runner code itself. So, it's
> not
> > >    readily apparent that we're comparing the main() methods and not the
> > >    application itself.
> > >
> > >
> > > On Mon, Apr 17, 2017 at 5:02 PM, Yi Pan <nickpan47@gmail.com> wrote:
> > >
> > > > Made some updates to clarify the role and functions of
> > RuntimeEnvironment
> > > > in SEP-2.
> > > >
> > > > On Fri, Apr 14, 2017 at 9:30 AM, Yi Pan <nickpan47@gmail.com> wrote:
> > > >
> > > > > Hi, everyone,
> > > > >
> > > > > In light of new features such as fluent API and standalone that
> > > introduce
> > > > > new deployment / application launch models in Samza, I created a
> new
> > > > SEP-2
> > > > > to address the new use cases. SEP-2 link: https://cwiki.apache.
> > > > > org/confluence/display/SAMZA/SEP-2%3A+ApplicationRunner+Design
> > > > >
> > > > > Please take a look and give feedbacks!
> > > > >
> > > > > Thanks!
> > > > >
> > > > > -Yi
> > > > >
> > > >
> > >
> >
>

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