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<a class="dropdown-item" tabindex="-1" href="ThreadsOverview.html#"><b>Chapter 1</b></a>
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<a class="dropdown-item" href="IntroConcSysOverview.html"> 1.1. Introduction to Concurrent Systems</a>
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<a class="dropdown-item" href="SysAndModels.html"> 1.2. Systems and Models</a>
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<a class="dropdown-item disabled"><b>Chapter 2</b></a>
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<a class="dropdown-item" href="ProcessesOverview.html"> 2.1. Processes and OS Basics</a>
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<a class="dropdown-item" href="Multiprogramming.html"> 2.2. Processes and Multiprogramming</a>
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<a class="dropdown-item" href="Extended2Processes.html"> 2.8. Extended Example: Listing Files with Processes</a>
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<a class="dropdown-item" href="IPCOverview.html"> 3.1. Concurrency with IPC</a>
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<a class="dropdown-item" href="IPCSems.html"> 3.8. Semaphores</a>
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<a class="dropdown-item" href="Extended3Bash.html"> 3.9. Extended Example: Bash-lite: A Simple Command-line Shell</a>
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<a class="dropdown-item" href="ThreadsOverview.html"> 6.1. Concurrency with Multithreading</a>
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<a class="dropdown-item" href="ProcVThreads.html"> 6.2. Processes vs. Threads</a>
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<a class="dropdown-item" href="Extended6Input.html"> 6.7. Extended Example: Keyboard Input Listener</a>
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<a class="dropdown-item" href="SynchOverview.html"> 7.1. Synchronization Primitives</a>
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<a class="dropdown-item" href="SynchProblemsOverview.html"> 8.1. Synchronization Patterns and Problems</a>
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<a class="dropdown-item" href="ProdCons.html"> 8.3. Producer-Consumer Problem</a>
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<a class="dropdown-item" href="ReadWrite.html"> 8.4. Readers-Writers Problem</a>
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<a class="dropdown-item" href="DiningPhil.html"> 8.5. Dining Philosophers Problem and Deadlock</a>
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<a class="dropdown-item" href="CigSmokers.html"> 8.6. Cigarette Smokers Problem and the Limits of Semaphores and Locks</a>
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<a class="dropdown-item" href="ParallelDistributedOverview.html"> 9.1. Parallel and Distributed Systems</a>
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<a class="dropdown-item" href="ParVConc.html"> 9.2. Parallelism vs. Concurrency</a>
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<a class="dropdown-item" href="ParallelDesign.html"> 9.3. Parallel Design Patterns</a>
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<a class="dropdown-item" href="Scaling.html"> 9.4. Limits of Parallelism and Scaling</a>
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<a class="dropdown-item" href="DistTiming.html"> 9.5. Timing in Distributed Environments</a>
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<a class="dropdown-item" href="DistDataStorage.html"> 9.6. Reliable Data Storage and Location</a>
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<a class="dropdown-item" href="DistConsensus.html"> 9.7. Consensus in Distributed Systems</a>
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<a class="dropdown-item" href="Extended9Blockchain.html"> 9.8. Extended Example: Blockchain Proof-of-Work</a>
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<a class="dropdown-item disabled"><b>Appendix A</b></a>
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<a class="dropdown-item" href="CLangOverview.html"> A.1. C Language Reintroduction</a>
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<a class="dropdown-item" href="Debugging.html"> A.2. Documentation and Debugging</a>
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<a class="dropdown-item" href="BasicTypes.html"> A.3. Basic Types and Pointers</a>
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<a class="dropdown-item" href="Arrays.html"> A.4. Arrays, Structs, Enums, and Type Definitions</a>
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<a class="dropdown-item" href="Pointers.html"> A.6. Pointers and Dynamic Allocation</a>
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<script>ODSA.SETTINGS.DISP_MOD_COMP = true;ODSA.SETTINGS.MODULE_NAME = "ThreadsOverview";ODSA.SETTINGS.MODULE_LONG_NAME = "Concurrency with Multithreading";ODSA.SETTINGS.MODULE_CHAPTER = "Concurrency with Multithreading"; ODSA.SETTINGS.BUILD_DATE = "2021-06-11 17:38:24"; ODSA.SETTINGS.BUILD_CMAP = false;JSAV_OPTIONS['lang']='en';JSAV_EXERCISE_OPTIONS['code']='java';</script><div class="section" id="concurrency-with-multithreading">
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<h1>6.1. Concurrency with Multithreading<a class="headerlink" href="ThreadsOverview.html#concurrency-with-multithreading" title="Permalink to this headline">¶</a></h1>
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<div class="figure mb-2 align-center" style="width: 100%">
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<a class="reference internal image-reference" href="_images/CSF-Timeline.6.png"><img class="p-3 mb-2 align-center border border-dark rounded-lg" alt="Timeline of major CSF topics with Multicore and Threads highlighted" src="_images/CSF-Timeline.6.png" style="width: 90%;" /></a>
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</div>
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<blockquote class="blockquote text-center">
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<p>“The good news about computers is that they do what you tell them
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to do. The bad news is that they do what you tell them to do.”
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<footer class="blockquote-footer">Ted Nelson</footer>
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</blockquote><p>Plus ça change, plus c’est la même chose. Or put another way,
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everything old is new again. IBM OS/360 introduced threads in 1967. The 1990s
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brought renewed interest in threads, with POSIX.1c-1995 standardizing their
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||
interface. One key factor behind this interest was the development of Linux as
|
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an open-source platform for cluster systems. Another factor was the impact of
|
||
the “power wall” on Moore’s law and integrated circuit design. As a result of
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this resurgence, threads are now unavoidable as a core abstraction in modern
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computing.</p>
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<div class="topic border border-dark rounded-lg bg-light px-2 mb-3">
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<div class="figure align-left" style="width: 5%">
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<a class="reference internal image-reference" href="_images/CSF-Images-Objectives.png"><img alt="Decorative chapter objectives image" src="_images/CSF-Images-Objectives.png" style="width: 100%;" /></a>
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</div>
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<p class="topic-title first pt-2 mb-1">Chapter Objectives</p><hr class="mt-1" />
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<p>In this chapter, we will address the following instructional objectives:</p>
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<ul class="simple">
|
||
<li>We will compare and contrast the concepts of threads and processes,
|
||
describing the advantages and limitations of each.</li>
|
||
<li>We will examine code using the POSIX thread library, a library that is widely
|
||
available on a variety of platforms.</li>
|
||
<li>We will explore race conditions as a new source of bugs that arise in
|
||
multithreaded software.</li>
|
||
<li>We will consider the benefits and drawbacks of using implicit threading
|
||
libraries and built-in language support.</li>
|
||
</ul>
|
||
</div>
|
||
<p>Throughout the first part of this book, we referred to processes whenever we
|
||
were discussing a unit of execution. Specifically, in
|
||
<a class="reference external" href="Multiprogramming.html">Processes and Multiprogramming</a>, we described
|
||
multiprogramming as the technique of dividing time on the CPU among multiple
|
||
processes. After one process ran for a certain amount of time, the kernel would
|
||
change the virtual address space to switch the execution context to a different
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||
process.</p>
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||
<p>While process context switching provides a robust mechanism for
|
||
multiprogramming, modern systems require a more efficient approach.
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||
Specifically, many programmers write applications or systems programs that
|
||
achieve concurrency by switching between multiple <a class="reference internal" href="Glossary.html#term-thread"><span class="xref std std-term">threads of execution</span></a>
|
||
(or, more simply, <a class="reference internal" href="Glossary.html#term-thread"><span class="xref std std-term">threads</span></a>) within a single process. This technique is
|
||
known as <a class="reference internal" href="Glossary.html#term-multithreading"><span class="xref std std-term">multithreading</span></a>.</p>
|
||
<p>There are many different languages and software libraries available for writing
|
||
multithreaded code. Some of these options are unique to a single operating
|
||
system or programming language, while others are more broadly supported. In this
|
||
and later chapters, we will primarily focus on using the POSIX library (called
|
||
<a class="reference internal" href="Glossary.html#term-pthreads"><span class="xref std std-term">pthreads</span></a>), a C library available on all major platforms, though we will
|
||
also explore some of the benefits of alternative approaches.</p>
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</div>
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