Control the step execution order
How to control the order in which steps get executed
By default, ZenML uses the data flowing between steps of your pipeline to determine the order in which steps get executed. The following example shows a pipeline in which step_3 depends on the outputs of step_1 and step_2. This means that ZenML can execute both step_1 and step_2 in parallel but needs to wait until both are finished before step_3 can be started.
from zenml.pipelines import pipeline
@pipeline
def example_pipeline(step_1, step_2, step_3):
step_1_output = step_1()
step_2_output = step_2()
step_3(step_1_output, step_2_output)
If you have additional constraints on the order in which steps get executed, you can specify non-data dependencies by calling step.after(some_other_step):
from zenml.pipelines import pipeline
@pipeline
def example_pipeline(step_1, step_2, step_3):
step_1.after(step_2)
step_1_output = step_1()
step_2_output = step_2()
step_3(step_1_output, step_2_output)
This pipeline is similar to the one explained above, but this time ZenML will make sure to only start step_1 after step_2 has finished.
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