---
id: threadpoolctl
version: "3.6.0"
license: BSD-3-Clause
license_treatment: permissive
maintenance: active
---

# threadpoolctl — threadpoolctl

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install threadpoolctl
uv add threadpoolctl
poetry add threadpoolctl

## Description

# Thread-pool Controls [![Build Status](https://github.com/joblib/threadpoolctl/actions/workflows/test.yml/badge.svg?branch=master)](https://github.com/joblib/threadpoolctl/actions?query=branch%3Amaster) [![codecov](https://codecov.io/gh/joblib/threadpoolctl/branch/master/graph/badge.svg)](https://codecov.io/gh/joblib/threadpoolctl)

Python helpers to limit the number of threads used in the
threadpool-backed of common native libraries used for scientific
computing and data science (e.g. BLAS and OpenMP).

Fine control of the underlying thread-pool size can be useful in
workloads that involve nested parallelism so as to mitigate
oversubscription issues.

## Installation

- For users, install the last published version from PyPI:

  ```bash
  pip install threadpoolctl
  ```

- For contributors, install from the source repository in developer
  mode:

  ```bash
  pip install -r dev-requirements.txt
  flit install --symlink
  ```

  then you run the tests with pytest:

  ```bash
  pytest
  ```

## Usage

### Command Line Interface

Get a JSON description of thread-pools initialized when importing python
packages such as numpy or scipy for instance:

```
python -m threadpoolctl -i...

## AI interpretation — verify before relying

Inspect and control the thread-pool size of native libraries like BLAS and OpenMP, preventing thread oversubscription in nested parallel workloads.

Verdict: Lightweight, actively maintained utility for controlling thread pools in scientific computing libraries. No security vulnerabilities, permissive license, and zero dependencies make it a safe dependency for projects needing fine-grained parallelism control.

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