Priority Weights¶
priority_weight
defines priorities in the executor queue. The default priority_weight
is 1
, and can be
bumped to any integer. Moreover, each task has a true priority_weight
that is calculated based on its
weight_rule
which defines weighting method used for the effective total priority weight of the task.
By default, Airflow’s weighting method is downstream
. You can find other weighting methods in
airflow.utils.WeightRule
.
There are three weighting methods.
downstream
The effective weight of the task is the aggregate sum of all downstream descendants. As a result, upstream tasks will have higher weight and will be scheduled more aggressively when using positive weight values. This is useful when you have multiple dag run instances and desire to have all upstream tasks to complete for all runs before each dag can continue processing downstream tasks.
upstream
The effective weight is the aggregate sum of all upstream ancestors. This is the opposite where downstream tasks have higher weight and will be scheduled more aggressively when using positive weight values. This is useful when you have multiple dag run instances and prefer to have each dag complete before starting upstream tasks of other dags runs.
absolute
The effective weight is the exact
priority_weight
specified without additional weighting. You may want to do this when you know exactly what priority weight each task should have. Additionally, when set toabsolute
, there is bonus effect of significantly speeding up the task creation process as for very large DAGs
The priority_weight
parameter can be used in conjunction with Pools.