Book Image

Python Parallel Programming Cookbook

By : Giancarlo Zaccone
Book Image

Python Parallel Programming Cookbook

By: Giancarlo Zaccone

Overview of this book

This book will teach you parallel programming techniques using examples in Python and will help you explore the many ways in which you can write code that allows more than one process to happen at once. Starting with introducing you to the world of parallel computing, it moves on to cover the fundamentals in Python. This is followed by exploring the thread-based parallelism model using the Python threading module by synchronizing threads and using locks, mutex, semaphores queues, GIL, and the thread pool. Next you will be taught about process-based parallelism where you will synchronize processes using message passing along with learning about the performance of MPI Python Modules. You will then go on to learn the asynchronous parallel programming model using the Python asyncio module along with handling exceptions. Moving on, you will discover distributed computing with Python, and learn how to install a broker, use Celery Python Module, and create a worker. You will understand anche Pycsp, the Scoop framework, and disk modules in Python. Further on, you will learnGPU programming withPython using the PyCUDA module along with evaluating performance limitations.
Table of Contents (13 chapters)
Python Parallel Programming Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Thread communication using a queue


As discussed earlier, threading can be complicated when threads need to share data or resources. As we saw, the Python threading module provides many synchronization primitives, including semaphores, condition variables, events, and locks. While these options exist, it is considered a best practice to instead concentrate on using the module queue. Queues are much easier to deal with and make threaded programming considerably safer, as they effectively funnel all access to a resource of a single thread and allow a cleaner and more readable design pattern.

We will simply consider these four queue methods:

  • put(): This puts an item in the queue

  • get(): This removes and returns an item from the queue

  • task_done(): This needs to be called each time an item has been processed

  • join(): This blocks until all items have been processed

How to do it…

In this example, we will see how to use the threading module with the queue module. Also, we have two entities here that try...