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The homepage of joblib with user documentation is located on:

Getting the latest code

To get the latest code using git, simply type::

git clone git://

If you don't have git installed, you can download a zip or tarball of the latest code:


You can use pip to install joblib::

pip install joblib

from any directory or::

python install

from the source directory.


  • Joblib has no mandatory dependencies besides Python (supported versions are 2.7+ and 3.4+).
  • Joblib has an optional dependency on Numpy (at least version 1.6.1) for array manipulation.
  • Joblib includes its own vendored copy of loky <>_ for process management.
  • Joblib can efficiently dump and load numpy arrays but does not require numpy to be installed.
  • Joblib has an optional dependency on python-lz4 <>_ as a faster alternative to zlib and gzip for compressed serialization.
  • Joblib has an optional dependency on psutil to mitigate memory leaks in parallel worker processes.
  • Some examples require external dependencies such as pandas. See the instructions in the Building the docs_ section for details.

Workflow to contribute

To contribute to joblib, first create an account on github <>. Once this is done, fork the joblib repository <> to have your own repository, clone it using 'git clone' on the computers where you want to work. Make your changes in your clone, push them to your github account, test them on several computers, and when you are happy with them, send a pull request to the main repository.

Running the test suite

To run the test suite, you need the pytest (version >= 3) and coverage modules. Run the test suite using::

pytest joblib

from the root of the project.

Building the docs

To build the docs you need to have sphinx (>=1.4) and some dependencies installed::

pip install -U -r .readthedocs-requirements.txt

The docs can then be built with the following command::

make doc

The html docs are located in the doc/_build/html directory.

Making a source tarball

To create a source tarball, eg for packaging or distributing, run the following command::

python sdist

The tarball will be created in the dist directory. This command will compile the docs, and the resulting tarball can be installed with no extra dependencies than the Python standard library. You will need setuptool and sphinx.

Making a release and uploading it to PyPI

This command is only run by project manager, to make a release, and upload in to PyPI::

python sdist bdist_wheel upload_docs --upload-dir doc/_build/html
twine upload dist/*

Updating the changelog

Changes are listed in the CHANGES.rst file. They must be manually updated but, the following git command may be used to generate the lines::

git log --abbrev-commit --date=short --no-merges --sparse


joblib is BSD-licenced (3 clause):

This software is OSI Certified Open Source Software.
OSI Certified is a certification mark of the Open Source Initiative.

Copyright (c) 2009-2011, joblib developpers
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

* Neither the name of Gael Varoquaux. nor the names of other joblib
  contributors may be used to endorse or promote products derived from
  this software without specific prior written permission.

**This software is provided by the copyright holders and contributors
"as is" and any express or implied warranties, including, but not
limited to, the implied warranties of merchantability and fitness for
a particular purpose are disclaimed. In no event shall the copyright
owner or contributors be liable for any direct, indirect, incidental,
special, exemplary, or consequential damages (including, but not
limited to, procurement of substitute goods or services; loss of use,
data, or profits; or business interruption) however caused and on any
theory of liability, whether in contract, strict liability, or tort
(including negligence or otherwise) arising in any way out of the use
of this software, even if advised of the possibility of such

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