# Join - controllare perché diverso

## Description

The **Join** action is used to synchronize parallel branches in a workflow. It acts as a control point that **waits for all preceding parallel branches at the same level** to complete before continuing with the next action(s).

This eliminates the need to create separate child workflows solely for the purpose of joining and continuing execution after parallel tasks have completed.

## Usage

Traditionally in Apache Hop, if you wanted to run parts of a workflow in parallel and then continue with a sequential flow, you would isolate those parallel sections in a child workflow. This was necessary to prevent downstream actions from being executed prematurely.

With the new **Join** action, this workaround is no longer needed.

To use the Join action:

1. Configure your workflow with multiple outgoing hops from a single action.
2. Enable **parallel execution** on the outgoing hops you want to run in parallel.
3. Add the **Join** action at the point where all parallel branches converge.
4. Connect all parallel branches to the **Join** action with regular (non-parallel) hops.
5. Connect the **Join** action to the next action you want to execute **after all parallel tasks have finished**.

## Example Workflow Structure

When executed:

* The actions `pipeline-1`, `pipeline-2` and `pipeline-3` run in parallel.
* The `join` action waits until `pipeline-1`, `pipeline-2` and `pipeline-3` are finished.
* Once they complete, the workflow continues with final action `check-datasets`.

## Benefits

* **Simplifies parallel execution:** No need for a separate child workflow just to coordinate branches.
* **Improves readability:** Your parallel and sequential logic can be maintained in a single workflow.
* **Increases maintainability:** Fewer components and external dependencies (child workflows) to manage.


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