The parallelism of a stream is always that of its producing operator

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votes

In https://ci.apache.org/projects/flink/flink-docs-release-1.8/concepts/programming-model.html#parallel-dataflows, there is a description

The number of operator subtasks is the parallelism of that particular operator. The parallelism of a stream is always that of its producing operator. Different operators of the same program may have different levels of parallelism.

I don't understand what The parallelism of a stream is always that of its producing operator. means, could someone please help explain more? Thanks！

1
apache-flink

1 Answers

1
votes

This statement isn't saying anything profound, imo. Operators produce streams. Operators have one or more parallel instances, sometimes referred to as subtasks, each of which is producing a portion of the stream.