To try Parsl now (without installing any code locally), experiment with our hosted tutorial notebooks on Binder.


Parsl is available on PyPI and conda-forge.

Parsl requires Python3.5+ and has been tested on Linux and macOS.

Installation using Pip

While pip can be used to install Parsl, we suggest the following approach for reliable installation when many Python environments are available.

  1. Install Parsl:

    $ python3 -m pip install parsl

To update a previously installed parsl to a newer version, use: python3 -m pip install -U parsl

Installation using Conda

  1. Create and activate a new conda environment:

    $ conda create --name parsl_py37 python=3.7
    $ source activate parsl_py37
  2. Install Parsl:

    $ python3 -m pip install parsl
    $ conda config --add channels conda-forge
    $ conda install parsl

The conda documentation provides instructions for installing conda on macOS and Linux.

Getting started

Parsl enables concurrent execution of Python functions (python_app) or external applications (bash_app). Developers must first annotate functions with Parsl decorators. When these functions are invoked, Parsl will manage the asynchronous execution of the function on specified resources. The result of a call to a Parsl app is an AppFuture.

The following example shows how to write a simple Parsl program with hello world Python and Bash apps.

import parsl
from parsl import python_app, bash_app


def hello_python (message):
    return 'Hello %s' % message

def hello_bash(message, stdout='hello-stdout'):
    return 'echo "Hello %s"' % message

# invoke the Python app and print the result
print(hello_python('World (Python)').result())

# invoke the Bash app and read the result from a file
hello_bash('World (Bash)').result()

with open('hello-stdout', 'r') as f:


The best way to learn more about Parsl is by reviewing the Parsl tutorials. There are several options for following the tutorial:

  1. Use Binder to follow the tutorial online without installing or writing any code locally.

  2. Clone the Parsl tutorial repository using a local Parsl installation.

  3. Read through the online tutorial documentation.

Usage Tracking

To help support the Parsl project, we ask that users opt-in to anonymized usage tracking whenever possible. Usage tracking allows us to measure usage, identify bugs, and improve usability, reliability, and performance. Only aggregate usage statistics will be used for reporting purposes.

As an NSF-funded project, our ability to track usage metrics is important for continued funding.

You can opt-in by setting PARSL_TRACKING=true in your environment or by setting usage_tracking=True in the configuration object (parsl.config.Config).

To read more about what information is collected and how it is used see Usage statistics collection.

For Developers

Parsl is an open source community that encourages contributions from users and developers. A guide for contributing to Parsl is available in the Parsl GitHub repository.

The following instructions outline how to set up Parsl from source.

  1. Download Parsl:

    $ git clone https://github.com/Parsl/parsl
  2. Install:

    $ cd parsl
    $ pip install .
    ( To install specific extra options from the source :)
    $ pip install '.[<optional_package1>...]'
  3. Use Parsl!