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From Chesnay Schepler <chesnay.schep...@fu-berlin.de>
Subject Re: Tuple
Date Tue, 04 Aug 2015 12:31:28 GMT
i think this job would be chained completely and never do any serialization.

On 04.08.2015 14:25, Matthias J. Sax wrote:
> Works for batch job, too. See enclosed.
> On 08/04/2015 01:34 PM, Matthias J. Sax wrote:
>> Yes, that is was the program does. However, streaming is not lazy so
>> deserialization should have happened.
>> I will try a batch job, later today.
>> On 08/04/2015 01:27 PM, Chesnay Schepler wrote:
>>> so I'm not to much into the streaming API, but as i see it this program
>>> creates an infinite number of tuples and then counts them, right?
>>> The problem with serialization as i understand it is that the receiver
>>> can't tell how many Tuple0 are sent, since you never actually read any
>>> data when deserializing a tuple. it's even more likely that it's not
>>> even attempted.
>>> As such, I'd be curious to see what happens when you create a batch job
>>> that with a limited number of starting tuples.
>>> On 04.08.2015 13:08, Matthias J. Sax wrote:
>>>> Hi,
>>>> I just opened a PR for this. https://github.com/apache/flink/pull/983
>>>> However, I was not able to "reproduce" serialization issues... I tested
>>>> Tuple0 (see enclosed code) in a cluster, and the program worked. Do I
>>>> miss anything?
>>>> -Matthias
>>>> On 08/03/2015 01:01 AM, Matthias J. Sax wrote:
>>>>> Thanks for the advice about Tuple0.
>>>>> I personally don't see any advantage in having "flink-tuple" project.
>>>>> I miss anything about it? Furthermore, I am not sure if it is a good
>>>>> idea the have too many too small projects.
>>>>> On 08/03/2015 12:48 AM, Stephan Ewen wrote:
>>>>>> Tuple0 would need special serialization and comparator logic. If
>>>>>> that is
>>>>>> given, I see no reason not to support it.
>>>>>> There is BTW, the request to create a dedicated "flink-tuple"
>>>>>> project, that
>>>>>> only contains the tuple classes. Any opinions on that?
>>>>>> On Mon, Aug 3, 2015 at 12:45 AM, Matthias J. Sax <
>>>>>> mjsax@informatik.hu-berlin.de> wrote:
>>>>>>> Thanks for the explanation!
>>>>>>> As I mentioned before, Tuple0 might also be helpful for streaming.
>>>>>>> And I
>>>>>>> guess I will need it for Storm compatibility layer, too. (I need
>>>>>>> double check, but Storm supports zero-attribute-tuples, too).
>>>>>>> With regard to the information I collected during the discussion,
>>>>>>> vote
>>>>>>> for keeping Tuple0 in Flink core, and fix the serialization problem.
>>>>>>> Should we have another JIRA for this? Or should I extend the
>>>>>>> JIRA? (https://issues.apache.org/jira/browse/FLINK-2457)
>>>>>>> -Matthias
>>>>>>> On 08/03/2015 12:22 AM, Chesnay Schepler wrote:
>>>>>>>> First of all, it was a really good idea to start a discussion
>>>>>>>> about this.
>>>>>>>> So the general idea behind Tuple0 was this:
>>>>>>>> The Python API maps python tuples to flink tuples. Python
can have
>>>>>>>> empty
>>>>>>>> tuples, so i thought "well duh, let's make a Tuple0 class!".
>>>>>>>> i did
>>>>>>>> not wanna do is create some non-Tuple object to represent
>>>>>>>> tuples,
>>>>>>>> I'd rather have them treated the same, because it's less
work and
>>>>>>>> creates simpler code.
>>>>>>>> When transferring the plan to java, certain parameters for
>>>>>>>> are tuples, which can be empty aswell.
>>>>>>>> This is where the Tuple0 class is really useful, because
these empty
>>>>>>>> tuples go through the same logic as other tuples.
>>>>>>>> This is also why i want to keep the class, at least in the
>>>>>>>> project, for now.
>>>>>>>> For the actual program execution, I need a new solution.
Funny story,
>>>>>>>> while writing this reply i noticed that the Python API can't
>>>>>>>> Tuple0 at runtime aswell. ha...ha... -.-
>>>>>>>> Guess I now know what I'm working on next.
>>>>>>>> On 02.08.2015 21:24, Matthias J. Sax wrote:
>>>>>>>>> Can you elaborate how and why Python used Tuple0? If
it cannot be
>>>>>>>>> serialized similar to regular Tuples, what is the usage
>>>>>>>>> Python? Right
>>>>>>>>> now it seems, as there is no special serialization code
for Tuple0.
>>>>>>>>> I just want to understand the topic in detail.
>>>>>>>>> -Matthias
>>>>>>>>> On 08/01/2015 03:38 PM, Stephan Ewen wrote:
>>>>>>>>>> I think a Tuple0 cannot be implemented like the current
tuples, at
>>>>>>> least
>>>>>>>>>> with respect to runtime serialization.
>>>>>>>>>> The system makes the assumption that it makes progress
in consuming
>>>>>>>>>> bytes
>>>>>>>>>> when deserializing values. If a Tuple= never consumes
data from the
>>>>>>> byte
>>>>>>>>>> stream, this assumption is broken. It would need
at least one
>>>>>>>>>> marker
>>>>>>>>>> byte.
>>>>>>>>>> Then it effectively is a Tuple1<Byte> disgusing
itself as a tuple0.
>>>>>>>>>> On Sat, Aug 1, 2015 at 1:38 PM, Matthias J. Sax <
>>>>>>>>>> mjsax@informatik.hu-berlin.de> wrote:
>>>>>>>>>>> I just double checked. Scala does not have type
Tuple0. IMHO,
>>>>>>>>>>> it would
>>>>>>>>>>> be best to remove Tuple0 for consistency. Having
Tuple types is
>>>>>>>>>>> for
>>>>>>>>>>> consistency reason with Scala in the first place,
right? Please
>>>>>>>>>>> give
>>>>>>>>>>> feedback.
>>>>>>>>>>> -Matthias
>>>>>>>>>>> On 08/01/2015 01:04 PM, Matthias J. Sax wrote:
>>>>>>>>>>>> I see.
>>>>>>>>>>>> I think that it might be useful to have Tuple0,
because in rare
>>>>>>> cases,
>>>>>>>>>>>> you only want to "notify" a downstream operators
(taking about
>>>>>>>>>>>> streaming) that something happened but there
is no actual data
>>>>>>>>>>>> to be
>>>>>>>>>>>> processed. Furthermore, if Flink cannot deal
with Tuple0 it
>>>>>>>>>>>> should be
>>>>>>>>>>>> removed completely for consistency IMHO.
>>>>>>>>>>>> I will open a JIRA for it.
>>>>>>>>>>>> -Matthias
>>>>>>>>>>>> On 07/31/2015 10:44 PM, Chesnay Schepler
>>>>>>>>>>>>> also, I'm not sure if I ever sent a Tuple0
through a program, it
>>>>>>>>>>>>> could
>>>>>>>>>>>>> be that the system freaks out.
>>>>>>>>>>>>> On 31.07.2015 22:40, Chesnay Schepler
>>>>>>>>>>>>>> there's no specific reason. it was
added fairly recently by me
>>>>>>>>>>>>>> (mid of
>>>>>>>>>>>>>> april), and you're most likely the
second person to use it.
>>>>>>>>>>>>>> i didn't integrate into all our tuple
related stuff because,
>>>>>>>>>>>>>> well,
>>>>>>> i
>>>>>>>>>>>>>> never thought anyone would actually
need it, so i saved
>>>>>>>>>>>>>> myself the
>>>>>>>>>>>>>> trouble.
>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>> is there any specific reason,
why Tuple.getTupleClass(int
>>>>>>>>>>>>>>> arity)
>>>>>>>>>>>>>>> does
>>>>>>>>>>>>>>> not support arity zero? There
is a class Tuple0, but it
>>>>>>>>>>>>>>> cannot be
>>>>>>>>>>>>>>> generator by Tuple.getTupleClass(...).
Is it a missing
>>>>>>>>>>>>>>> feature (I
>>>>>>>>>>> would
>>>>>>>>>>>>>>> like to have it).
>>>>>>>>>>>>>>> -Matthias

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