SequentialExecutor in Airflow: What It Is and When to Use

The SequentialExecutor in Airflow is a simple task executor that runs one task at a time in sequence. It is mainly used for development or testing because it does not run tasks in parallel like other executors.

How It Works

The SequentialExecutor works like a single-lane road where only one car (task) can pass at a time. It picks one task from the queue and runs it fully before moving to the next task. This means tasks are executed one after another, never at the same time.

This executor is built into Airflow and does not require extra setup. It is simple and reliable but slow for large workflows because it cannot run multiple tasks in parallel. Think of it as a beginner's mode for Airflow task execution.

Example

This example shows how to configure Airflow to use the SequentialExecutor by setting it in the configuration file.

ini

[core]
executor = SequentialExecutor

Output

Airflow will run tasks one by one without parallelism.

When to Use

Use SequentialExecutor when you are just starting with Airflow or testing your workflows locally. It is perfect for learning or debugging because it is simple and predictable.

However, for production or workflows with many tasks, use executors that support parallelism like LocalExecutor or CeleryExecutor to speed up task processing.

Key Points

• Sequential execution: runs one task at a time.
• Simple setup: no extra services needed.
• Best for: development, testing, and learning.
• Not for production: slow for many tasks.

Key Takeaways

SequentialExecutor runs tasks one by one without parallelism.

It is easy to set up and good for testing or learning Airflow.

Not suitable for production workflows with many tasks.

Use other executors like LocalExecutor for faster task execution.

Configure it by setting executor = SequentialExecutor in airflow.cfg.