Registry / data / threadpoolctl

threadpoolctl

library3.6.0pypypi✓ verified 29d ago

Threadpoolctl is a Python library that provides helpers to limit the number of threads used in threadpool-backed native libraries, such as BLAS and OpenMP, commonly used in scientific computing and data science. The current version is 3.6.0, released on March 13, 2025. The library is actively maintained with regular updates to support new Python versions and improve functionality.

data ai-ml

pip install threadpoolctl

github ↗package ↗

INSTALL

IMPORT

SIG · THREADPOOLCTL

threadpoolctl

datapythonv3.6.0

Install

1.6s avg

Import

53ms

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v3.6.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.052s · 17.9MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.6s · import 0.054s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

threadpool_info

✓ from threadpoolctl import threadpool_info

Ensure correct import path to access threadpool_info function.

threadpool_limits

✓ from threadpoolctl import threadpool_limits

Ensure correct import path to access threadpool_limits function.

This script demonstrates how to introspect threadpool information and limit the number of threads used by BLAS libraries using threadpoolctl.

import numpy as np from threadpoolctl import threadpool_info, threadpool_limits # Introspect threadpool information info = threadpool_info() for lib in info: print(f"Library: {lib['internal_api']} ({lib['user_api']})") print(f" Version: {lib['version']}") print(f" Threads: {lib['num_threads']}") print(f" Path: {lib['filepath']}") # Limit threads for BLAS with threadpool_limits(limits=1, user_api='blas'): a = np.random.randn(1000, 1000) a_squared = a @ a

Debug

Known issues

breakingDropped official support for Python 3.8 in version 3.6.0.

fix

Upgrade to Python 3.9 or later to maintain compatibility.

affects: 3.6.0

gotchaUsing threadpoolctl with both libomp (LLVM OpenMP) and libiomp (Intel OpenMP) loaded may cause crashes or deadlocks.

fix

Ensure only one OpenMP library is loaded to prevent potential issues.

affects: All versions

breakingRequired package 'numpy' is not installed.

fix

Install the 'numpy' package using pip: `pip install numpy`

affects: All versions

breakingRequired package 'numpy' is not found. Ensure all necessary dependencies are installed.

fix

Install the missing package using 'pip install numpy' or ensure the package is listed in your project's 'requirements.txt' and installed.

affects: All versions

Errors

Common errors & fixes

ImportError: No module named 'threadpoolctl'

The 'threadpoolctl' library has not been installed in the current Python environment.

fix

pip install threadpoolctl

AttributeError: module 'threadpoolctl' has no attribute 'threadpool_limits'

The 'threadpool_limits' function (and 'threadpool_info') should be imported directly from the 'threadpoolctl' package, not accessed as an attribute of the top-level module.

fix

from threadpoolctl import threadpool_limits

RuntimeError: threadpoolctl cannot find any threadpool library loaded in this process

'threadpoolctl' could not detect any supported threadpool-backed native libraries (like OpenBLAS, MKL, or OpenMP) loaded in the current Python process.

fix

Ensure that libraries like NumPy or SciPy are imported and correctly linked to a threadpool-enabled BLAS/LAPACK implementation (e.g., OpenBLAS, MKL) before using 'threadpoolctl'.

Upgrade

Version history

3.6.0latest on PyPI · released Mar 13, 2025

Audit

Dependencies

No dependency data recorded yet.

Agent activity

23 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/joblib/threadpoolctl ↗

packagehttps://pypi.org/project/threadpoolctl/ ↗