Re: Kafka and Flink integration

Posted by Jürgen Thomann on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Kafka-and-Flink-integration-tp13792p14121.html

Hi Stephan,

do you know an easy way to find out if Kryo or POJO is used? I have an Object that would be a POJO, but it has one field that uses an object without a public no argument constructor. As I understood the documentation, this should result in Kryo being used.

Thanks,
Jürgen

On 03.07.2017 17:18, Stephan Ewen wrote:

Hi Urs!

Inside Flink (between Flink operators)

  - Kryo is not a problem, but types must be registered up front for good performance

  - Tuples and POJOs are often faster than the types that fall back to Kryo

Persistent-storage (HDFS, Kafka, ...)

  - Kryo is not recommended, because its binary data format is not stable. It changes between major Kryo versions and between Kryo setups with different type registrations.

  - A stable format with schema evolution support (Avro, Thrift, ...) is recommended here.

On Thu, Jun 22, 2017 at 9:28 AM, Urs Schoenenberger <[hidden email]> wrote:

Hi Greg,

do you have a link where I could read up on the rationale behind
avoiding Kryo? I'm currently facing a similar decision and would like to
get some more background on this.

Thank you very much,
Urs

On 21.06.2017 12:10, Greg Hogan wrote:
> The recommendation has been to avoid Kryo where possible.
>
> General data exchange: avro or thrift.
>
> Flink internal data exchange: POJO (or Tuple, which are slightly faster though less readable, and there is an outstanding PR to narrow or close the performance gap).
>
> Kryo is useful for types which cannot be modified to be a POJO. There are also cases where Kryo must be used because Flink has insufficient TypeInformation, such as when returning an interface or abstract type when the actual concrete type can be known.
>
>
>
>> On Jun 21, 2017, at 3:19 AM, nragon <[hidden email]> wrote:
>>
>> So, serialization between producer application -> kafka -> flink kafka
>> consumer will use avro, thrift or kryo right? From there, the remaining
>> pipeline can just use standard pojo serialization, which would be better?
>>
>>
>>
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>

--
Urs Schönenberger - [hidden email]

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