---
title: process
sidebarTitle: process
---

# `prefect.workers.process`



Module containing the Process worker used for executing flow runs as subprocesses.

To start a Process worker, run the following command:

```bash
prefect worker start --pool 'my-work-pool' --type process
```

Replace `my-work-pool` with the name of the work pool you want the worker
to poll for flow runs.

For more information about work pools and workers,
checkout out the [Prefect docs](https://docs.prefect.io/v3/concepts/work-pools/).


## Classes

### `ProcessJobConfiguration` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L57" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

**Methods:**

#### `from_template_and_values` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/base.py#L166" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
from_template_and_values(cls, base_job_template: dict[str, Any], values: dict[str, Any], client: 'PrefectClient | None' = None)
```

Creates a valid worker configuration object from the provided base
configuration and overrides.

Important: this method expects that the base_job_template was already
validated server-side.


#### `is_using_a_runner` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/base.py#L136" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
is_using_a_runner(self) -> bool
```

#### `json_template` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/base.py#L233" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
json_template(cls) -> dict[str, Any]
```

Returns a dict with job configuration as keys and the corresponding templates as values

Defaults to using the job configuration parameter name as the template variable name.

e.g.
```python
{
    key1: '{{ key1 }}',     # default variable template
    key2: '{{ template2 }}', # `template2` specifically provide as template
}
```


#### `prepare_for_flow_run` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L68" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
prepare_for_flow_run(self, flow_run: 'FlowRun', deployment: 'DeploymentResponse | None' = None, flow: 'APIFlow | None' = None, work_pool: 'WorkPool | None' = None, worker_name: str | None = None) -> None
```

#### `prepare_for_flow_run` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/base.py#L257" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
prepare_for_flow_run(self, flow_run: 'FlowRun', deployment: 'DeploymentResponse | None' = None, flow: 'APIFlow | None' = None, work_pool: 'WorkPool | None' = None, worker_name: str | None = None) -> None
```

Prepare the job configuration for a flow run.

This method is called by the worker before starting a flow run. It
should be used to set any configuration values that are dependent on
the flow run.

**Args:**
- `flow_run`: The flow run to be executed.
- `deployment`: The deployment that the flow run is associated with.
- `flow`: The flow that the flow run is associated with.
- `work_pool`: The work pool that the flow run is running in.
- `worker_name`: The name of the worker that is submitting the flow run.


#### `validate_working_dir` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L63" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
validate_working_dir(cls, v: Path | str | None) -> Path | None
```

### `ProcessVariables` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L94" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

**Methods:**

#### `model_json_schema` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/base.py#L424" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
model_json_schema(cls, by_alias: bool = True, ref_template: str = '#/definitions/{model}', schema_generator: Type[GenerateJsonSchema] = GenerateJsonSchema, mode: Literal['validation', 'serialization'] = 'validation') -> dict[str, Any]
```

TODO\: stop overriding this method - use GenerateSchema in ConfigDict instead?


### `ProcessWorkerResult` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L113" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Contains information about the final state of a completed process


### `ProcessWorker` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L117" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

**Methods:**

#### `run` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L225" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
run(self, flow_run: 'FlowRun', configuration: ProcessJobConfiguration, task_status: Optional[anyio.abc.TaskStatus[int]] = None) -> ProcessWorkerResult
```

#### `start` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/workers/process.py#L132" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
start(self, run_once: bool = False, with_healthcheck: bool = False, printer: Callable[..., None] = print) -> None
```

Starts the worker and runs the main worker loops.

By default, the worker will run loops to poll for scheduled/cancelled flow
runs and sync with the Prefect API server.

If `run_once` is set, the worker will only run each loop once and then return.

If `with_healthcheck` is set, the worker will start a healthcheck server which
can be used to determine if the worker is still polling for flow runs and restart
the worker if necessary.

**Args:**
- `run_once`: If set, the worker will only run each loop once then return.
- `with_healthcheck`: If set, the worker will start a healthcheck server.
- `printer`: A `print`-like function where logs will be reported.

