Executors are responsible for executing steps within a pipeline run. Once a run has launched and the the process for the run, or run worker, has been allocated and started, the executor assumes responsibility for execution. Executors can range from single-process serial executors all the way to managing per-step computational resources with a sophisticated control plane.

What executor is used is determined by two things. First, modes provide the possible set of executors one can use. In order to set this use the executor_defs property on ModeDefinition. Second, the execution config section of the run config determines the actual executor.

Example executors include:

The executor system is pluggable, and it is possible to write your own executor to target a different execution substrate. This is not well-documented, and the internal APIs continue to be in flux.