Re: [DISCUSS] FLIP-169: DataStream API for Fine-Grained Resource Requirements

Posted by Arvid Heise-4 on
URL: http://deprecated-apache-flink-mailing-list-archive.368.s1.nabble.com/DISCUSS-FLIP-169-DataStream-API-for-Fine-Grained-Resource-Requirements-tp51071p51223.html

Hi Yangze,

I like the general approach to bind requirements to slotsharing groups. I
think the current approach is also flexible enough that a user could simply
use ParameterTool or similar to use config values and wire that with their
slotgroups, such that different requirements can be tested without
recompilation. So I don't see an immediate need to provide a generic
solution for yaml configuration for now.

Looking at the programmatic interface though, I think we could improve by
quite a bit and I haven't seen these alternatives being considered in the
FLIP:
1) Add new class SlotSharingGroup that incorporates all ResourceSpec
properties. Instead of using group names, the user could directly configure
such an object.

        SlotSharingGroup ssg1 = new SlotSharingGroup("ssg-1"); // name
could also be omitted and auto-generated
        ssg1.setCPUCores(4);
        ...
        DataStream<Tuple2<String, Integer>> grades =
                GradeSource
                        .getSource(env, rate)

.assignTimestampsAndWatermarks(IngestionTimeWatermarkStrategy.create())
                        .slotSharingGroup(ssg1);
        DataStream<Tuple2<String, Integer>> salaries =
                SalarySource.getSource(env, rate)

.assignTimestampsAndWatermarks(IngestionTimeWatermarkStrategy.create())
                        .slotSharingGroup(ssg2);

        // run the actual window join program with the same slot sharing
group as grades
        DataStream<Tuple3<String, Integer, Integer>> joinedStream =
                runWindowJoin(grades, salaries,
windowSize).slotSharingGroup(ssg1);

Note that we could make it backward compatible by changing the proposed
StreamExecutionEnvironment#setSlotSharingGroupResource to
StreamExecutionEnvironment#registerSlotSharingGroup(SlotSharingGroup) and
then use the string name for further reference.

2) I'm also not sure on the StreamExecutionEnvironment#
setSlotSharingGroupResources. What's the benefit of the Map version over
having the simple setter? Even if the user has a map
slotSharingGroupResources, he could simply do
slotSharingGroupResources.forEach(env::setSlotSharingGroupResource);

3) Is defining the ExternalResource part of this FLIP? I don't see a
Public* class yet. I'd be also fine to cut the scope of this FLIP and
remove it for now and annotate ResourceSpec/SlotSharingGroup evolving.

4) We should probably use a builder pattern around
ResourceSpec/SlotSharingGroup as in the current ResourceSpec. I don't think
we need to fully specify that in the FLIP but it would be good to at least
say how they should be created by the user.



On Tue, Jun 8, 2021 at 10:58 AM Yangze Guo <[hidden email]> wrote:

> @Yang
> In short, the external resources will participate in resource
> deduction and be logically ensured, but requesting an external
> resource must still be done through config options with the current
> default resource allocation strategy.
> In FLIP-56, we abstract the logic of resource allocation to the
> `ResourceAllocationStrategy`. Currently, with its default
> implementation, ResourceManager would still allocate TMs with the same
> resource spec and the external resources of it are configured through
> the config option as well. So, in your case, you need to define the
> "external-resources" and "external-resources.disk.amount". Then, all
> the disk requirements defined in the SSG will be logically ensured, as
> there is no slot level isolation. If the disk space of a task manager
> cannot fulfill the disk requirement, RM will allocate a new one.
> In the future, we'd like to introduce a `ResourceAllocationStrategy`
> which allocates heterogeneous TMs according to the requirements. Then,
> user only needs to define the driver of external resources when
> needed.
> Also, regarding the resource isolation, we may provide a fine-grained
> mode in which each slot can only fetch the information of external
> resources it requires in the future. But that is out of the scope of
> this PR.
>
> Best,
> Yangze Guo
>
> On Tue, Jun 8, 2021 at 4:20 PM Yang Wang <[hidden email]> wrote:
> >
> > Thanks @Yangze for preparing this FLIP.
> >
> > I think this is a good start point for the community users to have a
> taste
> > on the fine-grained
> > resource management, which we all believe it could improve the Flink job
> > stability and
> > cluster utilization.
> >
> > I have a simple question about the extended resources. It is possible to
> > combine extended resources
> > with fine-grained resource management. Except for the GPU, FPGA and other
> > new computing devices,
> > maybe the disk resource is a more general use case. For example,
> different
> > SSG may have various
> > disk requirements based on the state. So we need to allocate enough
> > ephemeral storage resource for every
> > TaskManager pod in Kubernetes deployment. Otherwise, it might be evicted
> > due to running out of limits.
> >
> >
> > Best,
> > Yang
> >
> >
> > Xintong Song <[hidden email]> 于2021年6月8日周二 下午1:47写道：
> >
> > > I think being able to specify fine grained resource requirements
> without
> > > having to change the codes and recompile the job is indeed a good
> idea. It
> > > definitely improves the usability.
> > >
> > > However, this requires more careful designs, which probably deserves a
> > > separate thread. I'd be good to have that discussion, but maybe not
> block
> > > this feature on that.
> > >
> > > One idea concerning the configuration approach: As Yangze said, flink
> > > configuration options are supposed to take effect at cluster level. For
> > > updating job level specifics that are not suitable to be introduced as
> a
> > > config option, currently the only way is to pass them as program
> arguments.
> > > Would it make sense to introduce a general approach for overwriting
> such
> > > job specifics without re-compiling the job?
> > >
> > > Thank you~
> > >
> > > Xintong Song
> > >
> > >
> > >
> > > On Tue, Jun 8, 2021 at 1:23 PM Yangze Guo <[hidden email]> wrote:
> > >
> > > > @Wenlong
> > > > After another consideration, the config option approach I mentioned
> > > > above might not be appropriate. The resource requirements for SSG
> > > > should be a job level configuration and should no be set in the
> > > > flink-conf.
> > > >
> > > > I think we can define a JSON format, which would be the ResourceSpecs
> > > > mapped by the name of SSGs, for the resource requirements of a
> > > > specific job. Then, we allow user to configure the file path of that
> > > > JSON. The JSON will be only parsed in runtime, which allows user to
> > > > tune it without re-compiling the job.
> > > >
> > > > We can add another #setSlotSharingGroupResources for configuring the
> > > > file path of that JSON:
> > > > ```
> > > > /**
> > > >  * Specify fine-grained resource requirements for slot sharing groups
> > > > with the given resource JSON file. The existing resource
> > > >  * requirement of the same slot sharing group will be replaced.
> > > >  */
> > > > public StreamExecutionEnvironment setSlotSharingGroupResources(
> > > >         String pathToResourceJson);
> > > > ```
> > > >
> > > > WDYT?
> > > >
> > > > Best,
> > > > Yangze Guo
> > > >
> > > > On Tue, Jun 8, 2021 at 12:12 PM Yangze Guo <[hidden email]>
> wrote:
> > > > >
> > > > > Thanks for the feedbacks, Xintong and Wenlong!
> > > > >
> > > > > @Wenlong
> > > > > I think that is a good idea, adjust the resource without
> re-compiling
> > > > > the job will facilitate the tuning process.
> > > > > We can define a pattern "slot-sharing-group.resource.{ssg name}"
> > > > > (welcome any proposal for the prefix naming) for the resource spec
> > > > > config of a slot sharing group. Then, user can set the
> ResourceSpec of
> > > > > SSG "ssg1" by adding "slot-sharing-group.resource.ssg1: {cpu: 1.0,
> > > > > heap: 100m, off-heap: 100m....}". WDYT?
> > > > >
> > > > >
> > > > > Best,
> > > > > Yangze Guo
> > > > >
> > > > > On Tue, Jun 8, 2021 at 10:37 AM wenlong.lwl <
> [hidden email]>
> > > > wrote:
> > > > > >
> > > > > > Thanks Yangze for the flip, it is great for users to be able to
> > > > declare the
> > > > > > fine-grained resource requirements for the job.
> > > > > >
> > > > > > I have one minor suggestion: can we support setting resource
> > > > requirements
> > > > > > by configuration? Currently most of the config options in
> execution
> > > > config
> > > > > > can be configured by configuration, and it is very likely that
> users
> > > > need
> > > > > > to adjust the resource according to the performance of their job
> > > during
> > > > > > debugging,  Providing a configuration way will make it more
> > > convenient.
> > > > > >
> > > > > > Bests,
> > > > > > Wenlong Lyu
> > > > > >
> > > > > > On Thu, 3 Jun 2021 at 15:59, Xintong Song <[hidden email]
> >
> > > > wrote:
> > > > > >
> > > > > > > Thanks Yangze for preparing the FLIP.
> > > > > > >
> > > > > > > The proposed changes look good to me.
> > > > > > >
> > > > > > > As you've mentioned in the implementation plan, I believe one
> of
> > > the
> > > > most
> > > > > > > important tasks of this FLIP is to have the feature well
> > > documented.
> > > > It
> > > > > > > would be really nice if we can keep that in mind and start
> drafting
> > > > the
> > > > > > > documentation early.
> > > > > > >
> > > > > > > Thank you~
> > > > > > >
> > > > > > > Xintong Song
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > On Thu, Jun 3, 2021 at 3:13 PM Yangze Guo <[hidden email]>
> > > > wrote:
> > > > > > >
> > > > > > > > Hi, there,
> > > > > > > >
> > > > > > > > We would like to start a discussion thread on "FLIP-169:
> > > DataStream
> > > > > > > > API for Fine-Grained Resource Requirements"[1], where we
> propose
> > > > the
> > > > > > > > DataStream API for specifying fine-grained resource
> requirements
> > > in
> > > > > > > > StreamExecutionEnvironment.
> > > > > > > >
> > > > > > > > Please find more details in the FLIP wiki document [1].
> Looking
> > > > > > > > forward to your feedback.
> > > > > > > >
> > > > > > > > [1]
> > > > > > > >
> > > > > > >
> > > >
> > >
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-169+DataStream+API+for+Fine-Grained+Resource+Requirements
> > > > > > > >
> > > > > > > >
> > > > > > > > Best,
> > > > > > > > Yangze Guo
> > > > > > > >
> > > > > > >
> > > >
> > >
>