runtime.md

Runtimes

This version of coordinated supports the concept of workers running multiple language runtimes. The Python worker in the coordinate package can't run Go code, for instance. This feature was added in Go Coordinate 0.2.0.

Work Spec

If a work spec contains a key runtime, it is the name of a language runtime that is required to run that work spec. This is generally a short description such as python_2, go, or java_1.7. In the Go API, the runtime can be retrieved from the immutable WorkSpecMeta.Runtime field.

For backwards compatibility, an empty runtime string should generally be interpreted as equivalent to python_2.

Attempt Requests

AttemptRequest.Runtimes is a list of strings that are runtimes this worker is capable of handling. Work specs with runtimes that do not exactly match one of these strings are ignored. If the runtime list is empty, any runtime is considered acceptable.

A new Go-based worker could call

attempts := worker.RequestAttempts(coordinate.AttemptRequest{
        NumberOfWorkUnits: 20,
        Runtimes: []string{"go"},
})

The Python-compatible interface passes a runtime list containing of a single empty string.

Example

For a mixed Python/Go system, create a YAML file containing:

flows:
  a_python_spec:
    module: python.module
    run_function: coordinate_run

  a_go_spec:
    runtime: go
    task: task_name

Using the coordinate tool from the Python coordinate package, run coordinate flow flow.yaml, pointing at the file above.

The Python-based coordinate_worker will only retrieve and run work units from a_python_spec. A new Go-based worker, using the RequestAttempts call shown above, will only retrieve and run work units from a_go_spec.