Re: Question about Fields grouping

[Navin Ipe <na...@searchlighthealth.com>]

As long as the bolt ID remains the same, the tuple will continue going to
the same task. See this:
http://nrecursions.blogspot.in/2016/09/concepts-about-storm-you-need-to-know.html#fieldsgroupingdoesnotgetoverwhelmedwithdata

On Thu, Jun 23, 2016 at 3:41 PM, Navin Ipe <na...@searchlighthealth.com>
wrote:

> Good question. At least one thing I know is that when a worker dies, it
> won't be able to ack the tuples it received, so those tuples will fail and
> you need to write code in your Spout's fail() method to re-emit them.
> My best guess is that your tuple with key 1 will continue going to task 1
> when it is restarted.
> It'd help if someone could confirm.
>
> On Wed, Jun 22, 2016 at 8:39 PM, Evgeniy Khyst <ev...@gmail.com>
> wrote:
>
>> Hi,
>>
>> I can't find information how fields grouping works in case of worker fail.
>>
>> With fields grouping tuples are partitioned by some key and are sent to
>> different tasks.
>> Tuples with the same key goes to the same task.
>>
>> When a worker dies, the supervisor will restart it. If it continuously
>> fails on startup and is unable to heartbeat to Nimbus, Nimbus will reassign
>> the worker to another machine.
>>
>> Does it mean that while supervisor restarts node or Nimbus reassigns
>> worker, tuples that were processed by tasks on failed worker will be routed
>> to other tasks?
>>
>> If yes, is it possible that while worker is restarted tuples by fields
>> grouping are directed to some other task, after worker is successfully
>> restarted or reassigned, tuples will be routed to taks on just restarted
>> worker?
>>
>> In this case there is a chance that tuple with key "1", for example, will
>> be processed by task 1, while worker for task 2 is restarted. After
>> successful restart of worker new tuple emitted by spout with the same key
>> "1" will be routed to task 2 on just restarted worker, while tuple with key
>> "1" processing on task 1 is still in progress.
>>
>> Does Storm provide guarantee that described situation will never happen
>> and when using fields grouping all tuples with the same key will be
>> processed by the same task even in the case of worker failure?
>>
>>
>> Best regards,
>> Evgeniy
>>
>
>
>
> --
> Regards,
> Navin
>



-- 
Regards,
Navin