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From Stefan Richter <s.rich...@data-artisans.com>
Subject Re: Parallelism and stateful mapping with Flink
Date Wed, 07 Dec 2016 16:28:58 GMT

could you maybe provide the (minimal) code for the problematic job? Also, are you sure that
the keyBy is working on the correct key attribute?


> Am 07.12.2016 um 15:57 schrieb Andrew Roberts <aroberts@fuze.com>:
> Hello,
> I’m trying to perform a stateful mapping of some objects coming in from Kafka in a
parallelized flink job (set on the job using env.setParallelism(3)). The data source is a
kafka topic, but the partitions aren’t meaningfully keyed for this operation (each kafka
message is flatMapped to between 0-2 objects, with potentially different keys). I have a keyBy()
operator directly before my map(), but I’m seeing objects with the same key distributed
to different parallel task instances, as reported by getRuntimeContext().getIndexOfThisSubtask().
> My understanding of keyBy is that it would segment the stream by key, and guarantee that
all data with a given key would hit the same instance. Am I possibly seeing residual “keying”
from the kafka topic?
> I’m running flink 1.1.3 in scala. Please let me know if I can add more info.
> Thanks,
> Andrew

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