LiveLessons: Java Concurrency (2nd Edition) Douglas C. Schmidt (d.schmidt@vanderbilt.edu) Cornelius Vanderbilt Professor of Engineering (Computer Science), Associate Provost of Research, and Data Science Institute Co-Director at Vanderbilt University

Table of Contents

Course Summary

Course Topics

Course Objectives

Recommended Background

Java Source Code

Facebook Group

Additional Resources

About the Instructor

To help you program quality concurrent programs in Java, the 2nd edition of my LiveLessons course on LiveLessons course on Java Concurrency provides over 9.5 hours of videos that focus on the pattern-oriented techniques, tools, and methods covered in the following five lessons:

• Lesson 1 presents an overview of concurrency and concurrent programming in Java, focusing on how the layers in Java's software stack support the needs of concurrent programs. This lesson also motivates the benefits of concurrent software and examines key complexities associated with developing concurrent software.

• Lesson 2 covers the Java threading mechanisms that can run multiple computations simultaneously, focusing on many ways that concurrent programs can create, control, and terminate Java threads, which are the units of computations that can be scheduled to run concurrently within a process.

• Lesson 3 covers the synchronization mechanisms that Java provides to ensure that interactions between computations running in multiple threads occur in the right order, at the right time, and don't accidentally corrupt shared data.

• Lesson 4 presents several case studies of concurrent programming in Java, providing in depth analysis of how Java's threading and synchronization mechanisms covered in earlier lessons can be applied in practice.

• Lesson 5 explores how Java's threading and synchronization mechanisms are programmed internally, which can help developers understand the patterns and best practices of developing software that use Java's concurrency capabilities most efficiently and effectively.

• Lesson 1: Overview of Java Concurrency
  This lesson presents an overview of concurrency and concurrent programming in Java. This lesson first explores the motivations for concurrency and then outlines key layers in the Java architecture, focusing on how these layers support the needs of concurrent programs on a range of computing devices. Next, the lesson shows how the benefits of concurrency make it worth the time and effort needed to master the complexities of concurrent programming in Java. This lesson focuses primarily on concepts, although it does show several examples of concurrent Java code to illustrate key points.

• Lesson 2: Java Threading Mechanisms and Frameworks
  This lesson covers how to develop concurrent programs, the computations of which run simultaneously on one or more processor cores. The lesson first focuses on the mechanisms that Java provides to create, control, and terminate multiple threads, which are the units of computation that can be scheduled to run concurrently within a process. After covering the basics of Java threads, the lesson delves deeper into their structure and functionality, focusing on the key states in their lifecycle and showing how to manage them effectively. The lesson next covers the powerful services provided by the Java Executor framework, which decouples the creation and management of threads from the rest of the application logic and supports a range of fixed and variable-sized thread pools that run efficiently on modern multicore processors. Finally, this lesson describes key Java 8 features, such as functional interfaces, lambda expressions, method references, sequential and parallel streams, and completable futures, that support concurrency via the functional programming paradigm. Throughout this lesson, viewers see how concurrent Java applications and frameworks are developed by applying many Gang of Four and POSA patterns.

• Lesson 3: Java Synchronization Mechanisms
  This lesson covers the capabilities that Java provides to ensure interactions between threads running computations concurrently occur in the right order, at the right time, and don.t accidentally corrupt shared data. Some Java synchronization mechanisms covered in this lesson are based on Java programming language features, such as volatile variables, synchronized methods and statements, and built-in monitor objects. The lesson also covers classes provided by the Java java.util.concurrent package, including classes that have been in Java since early versions (such as AtomicLong, ReentrantLock, ReentrantReadWriteLock, Semaphore, ConditionObject, CountDownLatch, and CyclicBarrier), as well as classes added in recent versions of Java (such as StampedLock and Phaser). The lesson analyzes many sample mechanisms, both in applications and the java.util.concurrent package itself. Viewers learn how to develop correct and efficient concurrent programs, as well as how to understand common problems that arise when these mechanisms are applied incorrectly. The lesson also discusses how Java synchronization mechanisms are enhanced by applying many Gang of Four and POSA patterns.

• Lesson 4: Case Studies of Concurrent Programming in Java
  This lesson provides an in-depth analysis of how the Java threading and synchronization mechanisms covered in earlier lessons can be applied in practice. The first case study explores the design and implementation of a pattern-oriented framework containing two Java threads that alternate printing ping and pong on several types of computing displays. This example shows how the framework enables the use of multiple Java synchronizers to configure and coordinate the proper interactions between the ping and pong threads, as well as the main thread. The second case study analyzes the structure and functionality of another pattern-orientated framework that uses a pool of threads created and managed by the Java Executor framework, together with various Java synchronization mechanisms to mediate concurrent access to a fixed-size pool of resources. Once again, this executor can configure and use a range of Java synchronizers. The third case study explores the design and implementation of an application that downloads image content from remote web servers via various Java threading mechanisms and frameworks, including the Java ExecutorCompletionService framework. The fourth and final case study revises the image processing app from the third case study to demonstrate how Java 8 functional programming features, such as lambda expressions, method references, sequential and parallel streams, and completable futures can be applied to simplify the programming of concurrent apps.

• Lesson 5: Source Code Analysis of java.util.concurrent Classes
  This lesson explores how Java's threading and synchronization mechanisms are programmed internally. The first part of this lesson focuses on the structure and functionality of the Java Executor framework, including the various thread pool executors and the ExecutorCompletionService. The lesson also shows how these core Java framework classes are supported by various other classes, such as Future and FutureTask. The second part of this lesson analyzes the design and implementation of core Java synchronizers, such as ReentrantLock, ConditionObject, and Semaphore. As part of this analysis, we cover the structure and functionality of Java.s AbstractQueueSynchronizer class. The lesson doesn.t analyze every class or every line of code but instead focuses on the key patterns and idioms used to guide the implementation of classes in the java.util.concurrent package. Understanding the design and implementation of these classes can help programmers understand the patterns and best practices of developing software that uses Java.s concurrency capabilities effectively and efficiently.

Java Source Code

Facebook Group

Additional Resources

• My videos on object-oriented design and programming with C++ and Java, patterns and frameworks for concurrent and networked software, and Android middleware and systems programming mechanisms.

• The online supplement to Doug Lea's book Concurrent Programming in Java.: Design Principles and Pattern, 2nd Edition

About the Instructor

Dr. Douglas C. Schmidt is the inaugural Dean of the School of Computing, Data Sciences, and Physics at William and Mary. He is currently on leave from the Software Engineering Institute (SEI) at Carnegie Mellon University, where he is a Visiting Scientist.

Dr. Schmidt was previously the Cornelius Vanderbilt Professor of Engineering in Computer Science at Vanderbilt University, as well as the Associate Chair of Computer Science and a Senior Researcher at the Institute for Software Integrated Systems. From 2018 to 2022 Dr. Schmidt served as the Associate Provost of Research Development and Technologies and the Co-Director of the Data Science Institute at Vanderbilt University. In 2024 Dr. Schmidt was the President-appointed and Senate-confirmed Director of Operational Test and Evaluation, where he is responsible for overseeing the evaluation of the operational effectiveness, suitability, survivability, and (when necessary) lethality of United States defense systems to defend the homeland and prevail in conflict.

Dr. Schmidt is an internationally renowned and widely cited (an h-index of 94, a g-index of 213, an i10-index of 389, and a citation count of 50,000+) researcher whose work focuses on patterns, optimization techniques, and empirical analyses of object-oriented and component-based frameworks and model-driven engineering tools that facilitate the development of distributed real-time and embedded (DRE) middleware frameworks and mobile cloud computing applications on parallel platforms running over wireless/wired networks and embedded system interconnects. His recent research focuses on prompt engineering techniques and prompt patterns that enhance the accuracy and expressiveness of large language models (LLMs) and generative augmented intelligence platforms.

He has published 10+ books and 700+ papers (including 135+ journal papers) in top IEEE, ACM, IFIP, and USENIX technical journals, conferences, and books that cover a range of topics, including high-performance communication software systems, parallel processing for high-speed networking protocols, and distributed real-time and embedded (DRE) middleware with CORBA, Real-time Java, object-oriented patterns for concurrent and distributed systems, concurrent and networked software for mobile devices, and model-driven engineering tools. He has mentored and graduated 40+ Ph.D. and Masters students working on these research topics and has presented 600+ keynote addresses, invited talks, and tutorials on Generative AI, mobile cloud computing with Android, reusable patterns, concurrent object-oriented network programming, distributed system middleware at scores of technical conferences.

Dr. Schmidt has co-authored several books in the Pattern-Oriented Software Architecture series for Wiley & Sons edited by Frank Buschmann of Siemens, including Patterns for Concurrent and Networked Objects, A Pattern Language for Distributed Computing, and Patterns and Pattern Languages. He has also co-authored two books for Addison-Wesley on the topic of C++ Network Programming edited by Bjarne Stroustrup of AT&T Labs. He was a member of the writing team for the books Ultra-Large-Scale Systems: Software Challenge of the Future and Critical Code: Software Producibility for Defense. In addition, he has co-editored the first volume of the Pattern Languages of Program Design series by Addison-Wesley and the Object-Oriented Application Frameworks: Applications & Experiences series for Wiley & Sons.

In addition to his research, Dr. Schmidt has a taught scores of cutting-edge courses at Vanderbilt University, University of California Irvine, and Washington University St. Louis on topics relating to object-oriented design and programming, software patterns, middleware for distributed real-time and embedded systems, concurrent and networked programming with C++ and Java, and mobile cloud computing with Android. He co-taught one of the first ground-breaking cross-college University Courses at Vanderbilt on Tackling Big Problems with Mobile Cloud Computing. He received the 2015 Award for Excellence in Teaching by the Vanderbilt University School of Engineering. In addition, he's taught 10+ popular Coursera MOOCs at Vanderbilt on topics related to pattern-oriented software architecture and Android App Development to over 400,000 learners from around the world.

Dr. Schmidt has served as guest editor for feature topic issues on Applications of Augmented Reality for the IEEE Proceedings, Model-Driven Engineering for IEEE Computer magazine, middleware technologies for future communication networks for IEEE Networks magazine, Distributed Object Computing for the IEEE Communications Magazine, Distributed Object Computing for the USENIX Computing Systems Journal, and the Communications of the ACM special issues on Design Patterns and Object-Oriented Frameworks. Dr. Schmidt has also served as the editor of the C++ Report magazine and the Patterns++ section of C++ Report. Along with Steve Vinoski (Chief Architect of IONA Technologies' Orbix Object Request Broker), Dr. Schmidt co-authored the Object Interconnections column on distributed computing middleware for the C/C++ Users Journal.

From 2010 to 2014 Dr. Schmidt was a member of the Air Force Scientific Advisory Board (AF SAB), where he served as Vice Chair of a study on Cyber Situational Awareness for Air Force mission operations, as well as a study on sustaining hardware and software for US aircraft. He also served on the advisory board for the joint Navy/Army Future Airborne Capability Environment (FACE) initiative. From 2000 to 2003 Dr. Schmidt served as a Program Manager in the DARPA Information eXplotation Office (IXO) and Information Technology Office (ITO), where he led the national effort on QoS-enabled component middleware research in the Program Composition for Embedded Systems (PCES) program. In addition, he served as the co-chair for the Software Design and Productivity (SDP) Coordinating Group of the Federal government's multi-agency Information Technology Research and Development (IT R&D) Program, the collaborative IT research effort of the major Federal science and technology agencies. The SDP Coordinating Group formulates the multi-agency research agenda in fundamental software design. Dr. Schmidt also served as the Deputy Director of the DARPA Information Technology Office (ITO), where he helped to set the national IT research and development agenda and manage the autonomous systems, network-centric command and control systems, distributed real-time and embedded systems, and augmented cognition.

Dr. Schmidt was also formerly an Associate Professor in the Electrical and Computer Engineering department at the University of California, Irvine and an Associate Professor and Director of the Center for Distributed Object Computing in the Department of Computer Science and in the Department of Radiology at Washington University in St. Louis, Missouri, USA. In addition, he's been an adjunct professor of Software Engineering in the Institute for Software Research at the School of Computer Science at Carnegie Mellon University. He has also served as the Deputy Director of Research and Chief Technology Officer at the Software Engineering Institute, the Chief Technology Officer for PrismTech and the Chief Technology Officer at Zircon Computing, where he was responsible for technical vision, strategic directions, and growth.

Dr. Schmidt served as the Chair of the DoD Organic Software Infrastructure Workshop in 2018, the General Chair of the Software Product Line Conference in 2015, the Program Chair of the Interoperable Open Architecture 2012 and 2013 conferences; program co-chair for the 1st International Symposium on Secure Virtual Infrastructures; the general co-chair for the DEBS 2009 conference; general chair for the IEEE/ACM 2007 MODELS conference; program co-chair for the 2006 ACM GPCE conference; program chair for the ACM OOPSLA 2004 conference; vice chair for the middleware track at the 2004 IEEE Real-time Systems Symposium; general co-chair for the 2004 IEEE Real-time Technology and Application Symposium; program co-chair for 2003 IEEE Real-time Technology and Application Symposium; the program co-chair for the 2003 IFIP/ACM/USENIX Middleware International Conference on Distributed Systems Platforms; area vice-chair and session chair for Middleware at the 2003 IEEE International Conference on Distributed Computing Systems (ICDCS); Program co-chair for the 2002 International Symposium on Distributed Objects and Applications; Program Co-chair for the 2001 International Symposium on Distributed Objects and Applications; Area vice-chair and session chair for Middleware at the 2001 IEEE International Conference on Distributed Computing Systems (ICDCS); co-chair of the 2000 OMG Workshop on Real-time and Embedded CORBA; general chair of the 2000 IFIP/ACM International Middleware Conference; program chair for the 1996 USENIX Conference on Object-Oriented Technologies and Systems (COOTS); and the 1996 Pattern Languages of Programming conference.

In addition to his academic research/teaching and university/government service, Dr. Schmidt has three decades of experience developing DRE middleware, model-driven engineering tools, and mobile cloud computing apps. He has led the development of the ADAPTIVE Communication Environment (ACE), which is a set of widely used, freely-available object-oriented frameworks that contain a rich set of components that implement patterns for mission-critical DRE systems. Dr. Schmidt and the members of his research group in the Distributed Object Computing (DOC) Group at Institute for Software Intensive Systems at Vanderbilt University have used ACE to develop a high performance, real-time CORBA ORB endsystem called The ACE ORB (TAO), which is a real-time ORB endsystem that supports end-to-end quality-of-service guarantees over high-speed networks. In turn, ACE and TAO form the basis for the Component-Integrated ACE ORB (CIAO), which is a real-time CORBA Component Model (CCM) implementation built by the DOC Group. The DOC Group also developed CoSMIC, which is a collection of domain-specific modeling languages and their associated analysis/synthesis tools that support various phases of DRE system development, analysis, configuration, and deployment.

The middleware platforms pioneered by Dr. Schmidt constitute some of the most successful examples of software R&D ever transitioned from academia to industry, being used successfully by thousands of developers in hundreds of companies world-wide, including Defense, Aerospace, Finance, Telecommunications, Medical, Gaming, and Internet industries. In collaboration with his colleagues, Dr. Schmidt has applied these middleware platforms and model-driven tools on large-scale telecommunications systems, medical imaging systems, real-time avionic systems, and distributed interactive simulation systems projects at many companies, including BBN, Boeing, Cisco, Ericsson, Kodak, Lockheed Martin, Lucent, Motorola, Nokia, Nortel, Raytheon, Qualcomm, SAIC, Siemens, Sprint, and Telcordia.

Dr. Schmidt received B.A. and M.A. degrees in Sociology from the College of William and Mary in Williamsburg, Virginia, and an M.S. and a Ph.D. in Computer Science from the University of California, Irvine (UCI) in 1984, 1986, 1990, and 1994, respectively.

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Last modified 10:50:20 CDT 20 July 2020