Implementation:Apache Airflow Pool Management

Knowledge Sources	Apache Airflow
Domains	Resource_Management, ORM
Last Updated	2026-02-08 00:00 GMT

Overview

Concrete tool for managing task concurrency pools provided by the Airflow Pool model.

Description

The Pool class is a SQLAlchemy model representing a resource pool with a fixed number of slots. It provides CRUD operations for managing pools and methods for querying slot availability. The default_pool is automatically created and used by tasks that don't specify a pool.

Usage

Create pools via the Airflow UI, CLI, or API when you need to limit concurrent access to shared resources. Reference pools in task definitions via the pool parameter.

Code Reference

Source Location

Repository: Apache Airflow
File: airflow-core/src/airflow/models/pool.py
Lines: L75-382

Signature

class Pool(Base):
    __tablename__ = "slot_pool"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    pool: Mapped[str] = mapped_column(String(256), unique=True)
    slots: Mapped[int] = mapped_column(Integer, default=0)  # -1 for infinite
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    include_deferred: Mapped[bool] = mapped_column(Boolean, nullable=False)
    team_name: Mapped[str | None] = mapped_column(String(50), nullable=True)

    DEFAULT_POOL_NAME = "default_pool"

    @staticmethod
    def create_or_update_pool(
        name: str,
        slots: int,
        description: str,
        include_deferred: bool,
        session: Session,
    ) -> "Pool": ...

Import

from airflow.models.pool import Pool

I/O Contract

Inputs

Name	Type	Required	Description
pool (name)	str	Yes	Unique pool identifier (max 256 chars)
slots	int	Yes	Concurrency limit (-1 for unlimited)
description	str	No	Pool description
include_deferred	bool	Yes	Whether deferred tasks count against slots

Outputs

Name	Type	Description
Pool object	Pool	Created or updated pool record
Slot allocation	int	Available/occupied/queued/deferred/scheduled_or_active slot counts

Usage Examples

Pool Management

# Create a pool via CLI
airflow pools set my_pool 5 "Database connection pool"

# List pools
airflow pools list

# Reference pool in task
@task(pool="my_pool", pool_slots=2)
def heavy_db_task():
    ...

Related Pages

Implements Principle

Principle:Apache_Airflow_Monitoring_Operations

Requires Environment

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Principle

Implementation

Heuristic

Environment