Book Image

Clojure High Performance Programming

By : Shantanu Kumar
Book Image

Clojure High Performance Programming

By: Shantanu Kumar

Overview of this book

<p>Clojure is a young, dynamic, functional programming language that runs on the Java Virtual Machine. It is built with performance, pragmatism, and simplicity in mind. Like most general purpose languages, Clojure’s features have different performance characteristics that one should know in order to write high performance code.<br /><br />Clojure High Performance Programming is a practical, to-the-point guide that shows you how to evaluate the performance implications of different Clojure abstractions, learn about their underpinnings, and apply the right approach for optimum performance in real-world programs.<br /><br />This book discusses the Clojure language in the light of performance factors that you can exploit in your own code.</p> <p>You will also learn about hardware and JVM internals that also impact Clojure’s performance. Key features include performance vocabulary, performance analysis, optimization techniques, and how to apply these to your programs. You will also find detailed information on Clojure's concurrency, state-management, and parallelization primitives.</p> <p>This book is your key to writing high performance Clojure code using the right abstraction, in the right place, using the right technique.</p>
Table of Contents (15 chapters)
Clojure High Performance Programming
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Low-level concurrency


Non-cooperative concurrency and parallelism cannot be achieved without explicit hardware support. We discussed SMT and multicore processors in Chapter 4, Host Performance. Recall that every processor core has its own L1 cache and several cores share the L2 cache. The shared L2 cache provides a fast mechanism to the processor cores to coordinate their cache access, eliminating the comparatively expensive memory access. Additionally, a processor buffers the writes to memory into something known as a dirty write-buffer. This helps the processor issue a batch of memory update requests, reorders the instructions, and then determines the final value to write to memory, known as write absorption.

Hardware memory barrier instructions

Memory access reordering is great for a sequential (single-threaded) program performance, but it is hazardous for concurrent programs where the order of memory access in one thread may disrupt the expectations in another thread. The processor needs...