Hi Rui,
Not sure if I understand your question correctly. The two modes are not the
same:
{taskmanager.load-balance.mode: Slots} = {cluster.evenly-spread-out-slots:
true, slot.sharing-strategy: LOCAL_INPUT_PREFERRED}
{taskmanager.load-balance.mode: Tasks} = {cluster.evenly-spread-out-slots:
true, slot.sharing-strategy: TASK_BALANCED_PREFERRED}
Thanks,
Zhu
Rui Fan <1996fan...@gmail.com> 于2023年10月10日周二 10:27写道：
> Hi Zhu,
>
> Thanks for your feedback!
>
> >> 2. When it's set to Tasks, how to assign slots to TM?
> > It's option2 at the moment. However, I think it's just implementation
> > details and can be changed/refined later.
> >
> > As you mentioned in another comment, 'taskmanager.load-balance.mode' is
> > a user oriented configuration. The goal is to achieve load balance,
> while
> > the load can be defined as allocated slots or assigned tasks.
> > The 'Tasks' mode, just the same as what is proposed in the FLIP,
> currently
> > use the mechanism of 'cluster.evenly-spread-out-slots' to help to
> achieve
> > balanced number of tasks. It's not perfect, but has acceptable
> effectiveness
> > and lower implementation complexity.
> >
> > The 'Slots' mode is needed for compatible reasons. Users that are
> satisfied
> > with the current ability of 'cluster.evenly-spread-out-slots' can
> continue
> > using it after the config 'cluster.evenly-spread-out-slots' is
> deprecated.
>
> IIUC, the 'Slots' mode is needed for compatibility with
> 'cluster.evenly-spread-out-slots'.
> The reason I ask this question is: if the behavior and logic of 'Slots'
> and
> 'Tasks' are exactly the same, it feels a bit strange to define two
> enumerations.
> And it may cause confusion to users.
>
> If they are totally the same, how about combining them to SlotsAndTasks?
> It can be compatible with 'cluster.evenly-spread-out-slots', and avoid
> the redundant enum. Of course, if the name(SlotsAndTasks) is ugly,
> we can discuss it. The core idea is combining them.
>
> WDYT?
>
> Best,
> Rui
>
> On Mon, Oct 9, 2023 at 3:24 PM Zhu Zhu <reed...@gmail.com> wrote:
>
>> Thanks for the response, Rui and Yuepeng.
>>
>> >> Rui
>> > 1. The default value is None, right?
>> Exactly.
>>
>> > 2. When it's set to Tasks, how to assign slots to TM?
>> It's option2 at the moment. However, I think it's just implementation
>> details and can be changed/refined later.
>>
>> As you mentioned in another comment, 'taskmanager.load-balance.mode' is
>> a user oriented configuration. The goal is to achieve load balance, while
>> the load can be defined as allocated slots or assigned tasks.
>> The 'Tasks' mode, just the same as what is proposed in the FLIP, currently
>> use the mechanism of 'cluster.evenly-spread-out-slots' to help to achieve
>> balanced number of tasks. It's not perfect, but has acceptable
>> effectiveness
>> and lower implementation complexity.
>>
>> The 'Slots' mode is needed for compatible reasons. Users that are
>> satisfied
>> with the current ability of 'cluster.evenly-spread-out-slots' can continue
>> using it after the config 'cluster.evenly-spread-out-slots' is deprecated.
>>
>>
>> >> Yuepeng
>> I think what users want is load balance. The combination is implementation
>> details and should be transparent to users.
>>
>> Meanwhile, I think locality does not entirely conflict with load balance.
>> In fact,
>> they should be both considered when assigning tasks. Usually, state
>> locality
>> should have the highest priority, and input locality can also be taken
>> care
>> of when trying to balance tasks to slots and TMs. We can see that the most
>> important input locality, i.e. forward, is always covered in this FLIP
>> when
>> computing slot sharing groups. It can be further optimized if we find it
>> problematic.
>>
>> Thanks,
>> Zhu
>>
>> Yangze Guo <karma...@gmail.com> 于2023年10月8日周日 13:53写道：
>>
>>> Thanks for the updates, Rui.
>>>
>>> It does seem challenging to ensure evenness in slot deployment unless
>>> we introduce batch slot requests in SlotPool. However, one possibility
>>> is to add a delay of around 50ms during the SlotPool's resource
>>> requirement declaration to the ResourceManager, similar to the
>>> checkResourceRequirementsWithDelay in the SlotManager. In most cases,
>>> this delay would allow the SlotManager to see all resource
>>> requirements, then it can allocate the slot more evenly. As a side
>>> effect, it could also significantly reduce the number of RPC messages
>>> to the ResourceManager, which could become a single-point bottleneck
>>> in OLAP scenarios. WDYT?
>>>
>>> Best,
>>> Yangze Guo
>>>
>>> On Sat, Oct 7, 2023 at 5:52 PM Rui Fan <1996fan...@gmail.com> wrote:
>>> >
>>> > Hi Yangze,
>>> >
>>> > Thanks for your quick response!
>>> >
>>> > Sorry, I re-read the 2.2.2 part[1] about the Waiting Mechanism, I found
>>> > it isn't clear. The root cause of introducing the waiting mechanism is
>>> > that the slot requests are sent from JobMaster to SlotPool is
>>> > one by one instead of one whole batch. I have rewritten the 2.2.2 part,
>>> > please read it again in your free time.
>>> >
>>> > [1]
>>> https://cwiki.apache.org/confluence/display/FLINK/FLIP-370%3A+Support+Balanced+Tasks+Scheduling#FLIP370:SupportBalancedTasksScheduling-2.2.2Waitingmechanism
>>> >
>>> > Best,
>>> > Rui
>>> >
>>> > On Sat, Oct 7, 2023 at 4:34 PM Yangze Guo <karma...@gmail.com> wrote:
>>> >>
>>> >> Thanks for the clarification, Rui.
>>> >>
>>> >> I believe the root cause of this issue is that in the current
>>> >> DefaultResourceAllocationStrategy, slot allocation begins before the
>>> >> decision to PendingTaskManagers requesting is made. That can be fixed
>>> >> within the strategy without introducing another waiting mechanism. I
>>> >> think it would be better to address this issue within the scope of
>>> >> this FLIP. However, I don't have a strong opinion on it, it depends on
>>> >> your bandwidth.
>>> >>
>>> >>
>>> >> Best,
>>> >> Yangze Guo
>>> >>
>>> >> On Sat, Oct 7, 2023 at 4:16 PM Rui Fan <1996fan...@gmail.com> wrote:
>>> >> >
>>> >> > Hi Yangze,
>>> >> >
>>> >> > > 2. From my understanding, if user enable the
>>> >> > > cluster.evenly-spread-out-slots,
>>> >> > > LeastUtilizationResourceMatchingStrategy will be used to
>>> determine the
>>> >> > > slot distribution and the slot allocation in the three TM will be
>>> >> > > (taskmanager.numberOfTaskSlots=3):
>>> >> > > TM1: 3 slot
>>> >> > > TM2: 2 slot
>>> >> > > TM3: 2 slot
>>> >> >
>>> >> > When all tms are ready in advance, the three TM will be:
>>> >> > TM1: 3 slot
>>> >> > TM2: 2 slot
>>> >> > TM3: 2 slot
>>> >> >
>>> >> > For application mode, the resource manager doesn't apply for
>>> >> > TM in advance, and slots aren't enough before the third TM is ready.
>>> >> > So all slots of the second TM will be used up. The three TM will be:
>>> >> > TM1: 3 slot
>>> >> > TM2: 3 slot
>>> >> > TM3: 1 slot
>>> >> >
>>> >> > That's why the FLIP add some notes:
>>> >> >
>>> >> > All free slots are in the last TM, because ResourceManager doesn’t
>>> have the waiting mechanism, and it just requests 7 slots for this JobMaster.
>>> >> > Why is it acceptable?
>>> >> >
>>> >> > If we just add the waiting mechanism to JobMaster but not in
>>> ResourceManager, all free slots will be in the last TM. All slots of other
>>> TMs are offered to JM.
>>> >> > That is, only one TM may have fewer tasks than the other TMs. The
>>> difference between the number of tasks of other TMs is at most 1.So When p
>>> >> slotsPerTM, the problem can be ignored.
>>> >> > We can also suggest users, in cases that p is small, it's better to
>>> configure slotsPerTM to 1, or let p % slotsPerTM == 0.
>>> >> >
>>> >> > Please correct me if my understanding is wrong, thanks~
>>> >> >
>>> >> > Best,
>>> >> > Rui
>>> >> >
>>> >> > On Sun, Oct 1, 2023 at 7:38 PM Yangze Guo <karma...@gmail.com>
>>> wrote:
>>> >> >>
>>> >> >> Hi, Rui,
>>> >> >>
>>> >> >> 1. With the current mechanism, when physical slots are offered from
>>> >> >> TM, the JobMaster will start deploying tasks and synchronizing
>>> their
>>> >> >> states. With the addition of the waiting mechanism, IIUC, the
>>> >> >> JobMaster will deploy and synchronize the states of all tasks only
>>> >> >> after all resources are available. The task deployment and state
>>> >> >> synchronization both occupy the JobMaster's RPC main thread. In
>>> >> >> complex jobs with a lot of tasks, this waiting mechanism may
>>> increase
>>> >> >> the pressure on the JobMaster and increase the end-to-end job
>>> >> >> deployment time.
>>> >> >>
>>> >> >> 2. From my understanding, if user enable the
>>> >> >> cluster.evenly-spread-out-slots,
>>> >> >> LeastUtilizationResourceMatchingStrategy will be used to determine
>>> the
>>> >> >> slot distribution and the slot allocation in the three TM will be
>>> >> >> (taskmanager.numberOfTaskSlots=3):
>>> >> >> TM1: 3 slot
>>> >> >> TM2: 2 slot
>>> >> >> TM3: 2 slot
>>> >> >>
>>> >> >> Best,
>>> >> >> Yangze Guo
>>> >> >>
>>> >> >> On Sun, Oct 1, 2023 at 6:14 PM Rui Fan <1996fan...@gmail.com>
>>> wrote:
>>> >> >> >
>>> >> >> > Hi Shammon,
>>> >> >> >
>>> >> >> > Thanks for your feedback as well!
>>> >> >> >
>>> >> >> > > IIUC, the overall balance is divided into two parts: slot to
>>> TM and task
>>> >> >> > to slot.
>>> >> >> > > 1. Slot to TM is guaranteed by SlotManager in ResourceManager
>>> >> >> > > 2. Task to slot is guaranteed by the slot pool in JM
>>> >> >> > >
>>> >> >> > > These two are completely independent, what are the benefits of
>>> unifying
>>> >> >> > > these two into one option? Also, do we want to share the same
>>> >> >> > > option between SlotPool in JM and SlotManager in RM? This
>>> sounds a bit
>>> >> >> > > strange.
>>> >> >> >
>>> >> >> > Your understanding is totally right, the balance needs 2 parts:
>>> slot to TM
>>> >> >> > and task to slot.
>>> >> >> >
>>> >> >> > As I understand, the following are benefits of unifying them
>>> into one
>>> >> >> > option:
>>> >> >> >
>>> >> >> > - Flink users don't care about these principles inside of flink,
>>> they don't
>>> >> >> > know these 2 parts.
>>> >> >> > - If flink provides 2 options, flink users need to set 2 options
>>> for their
>>> >> >> > job.
>>> >> >> > - If one option is missed, the final result may not be good.
>>> (Users may
>>> >> >> > have questions when using)
>>> >> >> > - If flink just provides 1 option, enabling one option is
>>> enough. (Reduce
>>> >> >> > the probability of misconfiguration)
>>> >> >> >
>>> >> >> > Also, Flink’s options are user-oriented. Each option represents
>>> a switch or
>>> >> >> > parameter of a feature.
>>> >> >> > A feature may be composed of multiple components inside Flink.
>>> >> >> > It might be better to keep only one switch per feature.
>>> >> >> >
>>> >> >> > Actually, the cluster.evenly-spread-out-slots option is used
>>> between
>>> >> >> > SlotPool in JM and SlotManager in RM. 2 components to ensure
>>> >> >> > this feature works well.
>>> >> >> >
>>> >> >> > Please correct me if my understanding is wrong,
>>> >> >> > and looking forward to your feedback, thanks!
>>> >> >> >
>>> >> >> > Best,
>>> >> >> > Rui
>>> >> >> >
>>> >> >> > On Sun, Oct 1, 2023 at 5:52 PM Rui Fan <1996fan...@gmail.com>
>>> wrote:
>>> >> >> >
>>> >> >> > > Hi Yangze,
>>> >> >> > >
>>> >> >> > > Thanks for your feedback!
>>> >> >> > >
>>> >> >> > > > 1. Is it possible for the SlotPool to get the slot
>>> allocation results
>>> >> >> > > > from the SlotManager in advance instead of waiting for the
>>> actual
>>> >> >> > > > physical slots to be registered, and perform pre-allocation?
>>> The
>>> >> >> > > > benefit of doing this is to make the task deployment process
>>> smoother,
>>> >> >> > > > especially when there are a large number of tasks in the job.
>>> >> >> > >
>>> >> >> > > Could you elaborate on that? I didn't understand what's the
>>> benefit and
>>> >> >> > > smoother.
>>> >> >> > >
>>> >> >> > > > 2. If user enable the cluster.evenly-spread-out-slots, the
>>> issue in
>>> >> >> > > > example 2 of section 2.2.3 can be resolved. Do I understand
>>> it
>>> >> >> > > > correctly?
>>> >> >> > >
>>> >> >> > > The example assigned result is the final allocation result
>>> when flink
>>> >> >> > > user enables the cluster.evenly-spread-out-slots. We think the
>>> >> >> > > assigned result is expected, so I think your understanding is
>>> right.
>>> >> >> > >
>>> >> >> > > Best,
>>> >> >> > > Rui
>>> >> >> > >
>>> >> >> > > On Thu, Sep 28, 2023 at 1:10 PM Shammon FY <zjur...@gmail.com>
>>> wrote:
>>> >> >> > >
>>> >> >> > >> Thanks Yuepeng for initiating this discussion.
>>> >> >> > >>
>>> >> >> > >> +1 in general too, in fact we have implemented a similar
>>> mechanism
>>> >> >> > >> internally to ensure a balanced allocation of tasks to slots,
>>> it works
>>> >> >> > >> well.
>>> >> >> > >>
>>> >> >> > >> Some comments about the mechanism
>>> >> >> > >>
>>> >> >> > >> 1. This mechanism will be only supported in `SlotPool` or
>>> both `SlotPool`
>>> >> >> > >> and `DeclarativeSlotPool`? Currently the two slot pools are
>>> used in
>>> >> >> > >> different schedulers. I think this will also bring value to
>>> >> >> > >> `DeclarativeSlotPool`, but currently FLIP content seems to be
>>> based on
>>> >> >> > >> `SlotPool`, right?
>>> >> >> > >>
>>> >> >> > >> 2. In fine-grained resource management, we can set different
>>> resource
>>> >> >> > >> requirements for different nodes, which means that the
>>> resources of each
>>> >> >> > >> slot are different. What should be done when the slot
>>> selected by the
>>> >> >> > >> round-robin strategy cannot meet the resource requirements?
>>> Will this lead
>>> >> >> > >> to the failure of the balance strategy?
>>> >> >> > >>
>>> >> >> > >> 3. Is the assignment of tasks to slots balanced based on
>>> region or job
>>> >> >> > >> level? When multiple TMs fail over, will it cause the
>>> balancing strategy
>>> >> >> > >> to
>>> >> >> > >> fail or even worse? What is the current processing strategy?
>>> >> >> > >>
>>> >> >> > >> For Zhuzhu and Rui:
>>> >> >> > >>
>>> >> >> > >> IIUC, the overall balance is divided into two parts: slot to
>>> TM and task
>>> >> >> > >> to
>>> >> >> > >> slot.
>>> >> >> > >> 1. Slot to TM is guaranteed by SlotManager in ResourceManager
>>> >> >> > >> 2. Task to slot is guaranteed by the slot pool in JM
>>> >> >> > >>
>>> >> >> > >> These two are completely independent, what are the benefits
>>> of unifying
>>> >> >> > >> these two into one option? Also, do we want to share the same
>>> >> >> > >> option between SlotPool in JM and SlotManager in RM? This
>>> sounds a bit
>>> >> >> > >> strange.
>>> >> >> > >>
>>> >> >> > >> Best,
>>> >> >> > >> Shammon FY
>>> >> >> > >>
>>> >> >> > >>
>>> >> >> > >>
>>> >> >> > >> On Thu, Sep 28, 2023 at 12:08 PM Rui Fan <
>>> 1996fan...@gmail.com> wrote:
>>> >> >> > >>
>>> >> >> > >> > Hi Zhu Zhu,
>>> >> >> > >> >
>>> >> >> > >> > Thanks for your feedback here!
>>> >> >> > >> >
>>> >> >> > >> > You are right, user needs to set 2 options:
>>> >> >> > >> > - cluster.evenly-spread-out-slots=true
>>> >> >> > >> > - slot.sharing-strategy=TASK_BALANCED_PREFERRED
>>> >> >> > >> >
>>> >> >> > >> > Update it to one option is useful at user side, so
>>> >> >> > >> > `taskmanager.load-balance.mode` sounds good to me.
>>> >> >> > >> > I want to check some points and behaviors about this option:
>>> >> >> > >> >
>>> >> >> > >> > 1. The default value is None, right?
>>> >> >> > >> > 2. When it's set to Tasks, how to assign slots to TM?
>>> >> >> > >> > - Option1: It's just check task number
>>> >> >> > >> > - Option2: It''s check the slot number first, then check the
>>> >> >> > >> > task number when the slot number is the same.
>>> >> >> > >> >
>>> >> >> > >> > Giving an example to explain what's the difference between
>>> them:
>>> >> >> > >> >
>>> >> >> > >> > - A session cluster has 2 flink jobs, they are jobA and jobB
>>> >> >> > >> > - Each TM has 4 slots.
>>> >> >> > >> > - The task number of one slot of jobA is 3
>>> >> >> > >> > - The task number of one slot of jobB is 1
>>> >> >> > >> > - We have 2 TaskManagers:
>>> >> >> > >> > - tm1 runs 3 slots of jobB, so tm1 runs 3 tasks
>>> >> >> > >> > - tm2 runs 1 slot of jobA, and 1 slot of jobB, so tm2
>>> runs 4 tasks.
>>> >> >> > >> >
>>> >> >> > >> > Now, we need to run a new slot, which tm should offer it?
>>> >> >> > >> > - Option1: If we just check the task number, the tm1 is
>>> better.
>>> >> >> > >> > - Option2: If we check the slot number first, and then
>>> check task, the
>>> >> >> > >> tm2
>>> >> >> > >> > is better
>>> >> >> > >> >
>>> >> >> > >> > The original FLIP selected option2, that's why we didn't
>>> add the
>>> >> >> > >> > third option. The option2 didn't break the semantics when
>>> >> >> > >> > `cluster.evenly-spread-out-slots` is true, and it just
>>> improve the
>>> >> >> > >> > behavior without the semantics is changed.
>>> >> >> > >> >
>>> >> >> > >> > In the other hands, if we choose option2, when user set
>>> >> >> > >> > `taskmanager.load-balance.mode` is Tasks. It also can
>>> achieve
>>> >> >> > >> > the goal when it's Slots.
>>> >> >> > >> >
>>> >> >> > >> > So I think the `Slots` enum isn't needed if we choose
>>> option2.
>>> >> >> > >> > Of course, If we choose the option1, the enum is needed.
>>> >> >> > >> >
>>> >> >> > >> > Looking forward to your feedback, thanks~
>>> >> >> > >> >
>>> >> >> > >> > Best,
>>> >> >> > >> > Rui
>>> >> >> > >> >
>>> >> >> > >> > On Wed, Sep 27, 2023 at 9:11 PM Zhu Zhu <reed...@gmail.com>
>>> wrote:
>>> >> >> > >> >
>>> >> >> > >> > > Thanks Yuepeng and Rui for creating this FLIP.
>>> >> >> > >> > >
>>> >> >> > >> > > +1 in general
>>> >> >> > >> > > The idea is straight forward: best-effort gather all the
>>> slot requests
>>> >> >> > >> > > and offered slots to form an overview before assigning
>>> slots, trying
>>> >> >> > >> to
>>> >> >> > >> > > balance the loads of task managers when assigning slots.
>>> >> >> > >> > >
>>> >> >> > >> > > I have one comment regarding the configuration for ease
>>> of use:
>>> >> >> > >> > >
>>> >> >> > >> > > IIUC, this FLIP uses an existing config
>>> >> >> > >> 'cluster.evenly-spread-out-slots'
>>> >> >> > >> > > as the main switch of the new feature. That is, from user
>>> perspective,
>>> >> >> > >> > > with this improvement, the
>>> 'cluster.evenly-spread-out-slots' feature
>>> >> >> > >> not
>>> >> >> > >> > > only balances the number of slots on task managers, but
>>> also balances
>>> >> >> > >> the
>>> >> >> > >> > > number of tasks. This is a behavior change anyway.
>>> Besides that, it
>>> >> >> > >> also
>>> >> >> > >> > > requires users to set 'slot.sharing-strategy' to
>>> >> >> > >> > 'TASK_BALANCED_PREFERRED'
>>> >> >> > >> > > to balance the tasks in each slot.
>>> >> >> > >> > >
>>> >> >> > >> > > I think we can introduce a new config option
>>> >> >> > >> > > `taskmanager.load-balance.mode`,
>>> >> >> > >> > > which accepts "None"/"Slots"/"Tasks".
>>> >> >> > >> `cluster.evenly-spread-out-slots`
>>> >> >> > >> > > can be superseded by the "Slots" mode and get deprecated.
>>> In the
>>> >> >> > >> future
>>> >> >> > >> > > it can support more mode, e.g. "CpuCores", to work better
>>> for jobs
>>> >> >> > >> with
>>> >> >> > >> > > fine-grained resources. The proposed config option
>>> >> >> > >> > > `slot.request.max-interval`
>>> >> >> > >> > > then can be renamed to
>>> >> >> > >> > > `taskmanager.load-balance.request-stablizing-timeout`
>>> >> >> > >> > > to show its relation with the feature. The proposed
>>> >> >> > >> > `slot.sharing-strategy`
>>> >> >> > >> > > is not needed, because the configured "Tasks" mode will
>>> do the work.
>>> >> >> > >> > >
>>> >> >> > >> > > WDYT?
>>> >> >> > >> > >
>>> >> >> > >> > > Thanks,
>>> >> >> > >> > > Zhu Zhu
>>> >> >> > >> > >
>>> >> >> > >> > > Yuepeng Pan <panyuep...@apache.org> 于2023年9月25日周一
>>> 16:26写道：
>>> >> >> > >> > >
>>> >> >> > >> > >> Hi all,
>>> >> >> > >> > >>
>>> >> >> > >> > >>
>>> >> >> > >> > >> I and Fan Rui(CC’ed) created the FLIP-370[1] to support
>>> balanced
>>> >> >> > >> tasks
>>> >> >> > >> > >> scheduling.
>>> >> >> > >> > >>
>>> >> >> > >> > >>
>>> >> >> > >> > >> The current strategy of Flink to deploy tasks sometimes
>>> leads some
>>> >> >> > >> > >> TMs(TaskManagers) to have more tasks while others have
>>> fewer tasks,
>>> >> >> > >> > >> resulting in excessive resource utilization at some TMs
>>> that contain
>>> >> >> > >> > more
>>> >> >> > >> > >> tasks and becoming a bottleneck for the entire job
>>> processing.
>>> >> >> > >> > Developing
>>> >> >> > >> > >> strategies to achieve task load balancing for TMs and
>>> reducing job
>>> >> >> > >> > >> bottlenecks becomes very meaningful.
>>> >> >> > >> > >>
>>> >> >> > >> > >>
>>> >> >> > >> > >> The raw design and discussions could be found in the
>>> Flink JIRA[2]
>>> >> >> > >> and
>>> >> >> > >> > >> Google doc[3]. We really appreciate Zhu Zhu(CC’ed) for
>>> providing some
>>> >> >> > >> > >> valuable help and suggestions in advance.
>>> >> >> > >> > >>
>>> >> >> > >> > >>
>>> >> >> > >> > >> Please refer to the FLIP[1] document for more details
>>> about the
>>> >> >> > >> proposed
>>> >> >> > >> > >> design and implementation. We welcome any feedback and
>>> opinions on
>>> >> >> > >> this
>>> >> >> > >> > >> proposal.
>>> >> >> > >> > >>
>>> >> >> > >> > >>
>>> >> >> > >> > >> [1]
>>> >> >> > >> > >>
>>> >> >> > >> >
>>> >> >> > >>
>>> https://cwiki.apache.org/confluence/display/FLINK/FLIP-370%3A+Support+Balanced+Tasks+Scheduling
>>> >> >> > >> > >>
>>> >> >> > >> > >> [2] https://issues.apache.org/jira/browse/FLINK-31757
>>> >> >> > >> > >>
>>> >> >> > >> > >> [3]
>>> >> >> > >> > >>
>>> >> >> > >> >
>>> >> >> > >>
>>> https://docs.google.com/document/d/14WhrSNGBdcsRl3IK7CZO-RaZ5KXU2X1dWqxPEFr3iS8
>>> >> >> > >> > >>
>>> >> >> > >> > >>
>>> >> >> > >> > >> Best,
>>> >> >> > >> > >>
>>> >> >> > >> > >> Yuepeng Pan
>>> >> >> > >> > >>
>>> >> >> > >> > >
>>> >> >> > >> >
>>> >> >> > >>
>>> >> >> > >
>>>
>>
