Map Tasks

A map task lets you run a task over a list of inputs within a single workflow node. This means you can run thousands of instances of that task without creating a node for every instance, providing valuable performance gains. Furthermore you can run map tasks on alternate execution back-ends, such as AWS Batch which is a provisioned services that can scale to great sizes.

import typing

from flytekit import TaskMetadata, map_task, task, workflow

Note that this is the single task that we’ll use in our map task. It can only accept one input and produce one output although this may expand in the future.

def a_mappable_task(a: int) -> str:
    inc = a + 2
    stringified = str(inc)
    return stringified

def coalesce(b: typing.List[str]) -> str:
    coalesced = "".join(b)
    return coalesced

To use a map task in your workflow, use the flytekit.core.map_task function and pass in an individual task to be repeated across a collection of inputs. In this case the type of a, typing.List[int] is a list of the input type defined for a_mappable_task.

def my_map_workflow(a: typing.List[int]) -> str:
    mapped_out = map_task(a_mappable_task, metadata=TaskMetadata(retries=1))(a=a)
    coalesced = coalesce(b=mapped_out)
    return coalesced

if __name__ == "__main__":
    result = my_map_workflow(a=[1, 2, 3, 4, 5])

Total running time of the script: ( 0 minutes 0.000 seconds)

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