Distributed Computing with Python

Table of Contents

Distributed Computing with Python

Credits

About the Author

About the Reviewer

www.PacktPub.com

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Why subscribe?

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. An Introduction to Parallel and Distributed Computing

Parallel computing

Distributed computing

Shared memory versus distributed memory

Amdahl's law

The mixed paradigm

Summary

2. Asynchronous Programming

Coroutines

An asynchronous example

Summary

3. Parallelism in Python

Multiple threads

Multiple processes

Multiprocess queues

Closing thoughts

Summary

4. Distributed Applications – with Celery

Establishing a multimachine environment

Installing Celery

Testing the installation

A tour of Celery

More complex Celery applications

Celery in production

Celery alternatives – Python-RQ

Celery alternatives – Pyro

Summary

5. Python in the Cloud

Cloud computing and AWS

Creating an AWS account

Creating an EC2 instance

Storing data in Amazon S3

Amazon elastic beanstalk

Creating a private cloud

Summary

6. Python on an HPC Cluster

Your typical HPC cluster

Job schedulers

Running a Python job using HTCondor

Running a Python job using PBS

Debugging

Summary

7. Testing and Debugging Distributed Applications

The big picture

Common problems – clocks and time

Common problems – software environments

Common problems – permissions and environments

Common problems – the availability of hardware resources

Challenges – the development environment

A useful strategy – logging everything

A useful strategy – simulating components

Summary

8. The Road Ahead

The first two chapters

The tools

The cloud and the HPC world

Debugging and monitoring

Where to go next

Index

Distributed Computing with Python

Distributed Computing with Python

Copyright © 2016 Packt Publishing

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First published: April 2016

Production reference: 1060416

Published by Packt Publishing Ltd.

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ISBN 978-1-78588-969-1

www.packtpub.com

Credits

Author

Francesco Pierfederici

Reviewer

James King

Commissioning Editor

Veena Pagare

Acquisition Editor

Aaron Lazar

Content Development Editor

Parshva Sheth

Technical Editor

Abhishek R. Kotian

Copy Editor

Neha Vyas

Project Coordinator

Nikhil Nair

Proofreader

Safis Editing

Indexer

Rekha Nair

Graphics

Disha Haria

Production Coordinator

Melwyn Dsa

Cover Work

Melwyn Dsa

About the Author

Francesco Pierfederici is a software engineer who loves Python. He has been working in the fields of astronomy, biology, and numerical weather forecasting for the last 20 years.

He has built large distributed systems that make use of tens of thousands of cores at a time and run on some of the fastest supercomputers in the world. He has also written a lot of applications of dubious usefulness but that are great fun. Mostly, he just likes to build things.

I would like to thank my wife, Alicia, for her unreasonable patience during the gestation of this book. I would also like to thank Parshva Sheth and Aaron Lazar at Packt Publishing and the technical reviewer, James King, who were all instrumental in making this a better book.

About the Reviewer

James King is a software developer with a broad range of experience in distributed systems. He is a contributor to many open source projects including OpenStack and Mozilla Firefox. He enjoys mathematics, horsing around with his kids, games, and art.

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Preface

Parallel and distributed computing is a fascinating subject that only a few years ago developers in only a very few large companies and national labs were privy to. Things have changed dramatically in the last decade or so, and now everybody can build small- and medium-scale distributed applications in a variety of programming languages including, of course, our favorite one: Python.

This book is a very practical guide for Python programmers who are starting to build their own distributed systems. It starts off by illustrating the bare minimum theoretical concepts needed to understand parallel and distributed computing in order to lay the basic foundations required for the rest of the (more practical) chapters.

It then looks at some first examples of parallelism using nothing more than modules from the Python standard library. The next step is to move beyond the confines of a single computer and start using more and more nodes. This is accomplished using a number of third-party libraries, including Celery and Pyro.

The remaining chapters investigate a few deployment options for our distributed applications. The cloud and classic High Performance Computing (HPC) clusters, together with their strengths and challenges, take center stage.

Finally, the thorny issues of monitoring, logging, profiling, and debugging are touched upon.

All in all, this is very much a hands-on book, teaching you how to use some of the most common frameworks and methodologies to build parallel and distributed systems in Python.

What this book covers

Chapter 1, An Introduction to Parallel and Distributed Computing, takes you through the basic theoretical foundations of parallel and distributed computing.

Chapter 2, Asynchronous Programming, describes the two main programming styles used in distributed applications: synchronous and asynchronous programming.

Chapter 3, Parallelism in Python, shows you how to do more than one thing at the same time in your Python code, using nothing more than the Python standard library.

Chapter 4, Distributed Applications – with Celery, teaches you how to build simple distributed applications using Celery and some of its competitors: Python-RQ and Pyro.

Chapter 5, Python in the Cloud, shows how you can deploy your Python applications on the cloud using Amazon Web Services.

Chapter 6, Python on an HPC Cluster, shows how to deploy your Python applications on a classic HPC cluster, typical of many universities and national labs.

Chapter 7, Testing and Debugging Distributed Applications, talks about the challenges of testing, profiling, and debugging distributed applications in Python.

Chapter 8, The Road Ahead, looks at what you have learned so far and which directions interested readers could take to push their development of distributed systems further.

What you need for this book

The following software and hardware is recommended:

Python 3.5 or later

A laptop or desktop computer running Linux or Mac OS X

Ideally, some extra computers or some extra virtual machines to test your distributed applications

All software mentioned in this book is free of charge and can be downloaded from the Internet with the exception of PBS Pro, which is commercial. Most of the PBS Pro functionality, however, is available in its close sibling Torque, which is open source.

Who this book is for

This book is for developers who already know Python and want to learn how to parallelize their code and/or write distributed systems. While a Unix environment is assumed, most if not all of the examples should also work on Windows systems.

Conventions

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Chapter 1. An Introduction to Parallel and Distributed Computing

The first modern digital computer was invented in the late 30s and early 40s (that is, arguably, the Z1 from Konrad Zuse in 1936), probably before most of the readers of this book—let alone