57 lines
3.4 KiB
HTML
57 lines
3.4 KiB
HTML
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Contention among threads" />
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<meta name="abstract" content="Contention occurs when one thread has to wait for another thread to finish using a resource." />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<title>Contention among threads</title>
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</head>
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<body id="rzahwcon-conco"><a name="rzahwcon-conco"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Contention among threads</h1>
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<div><p>Contention occurs when one thread has to wait for another thread
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to finish using a resource.</p>
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<div class="section"><p>Contention problems can occur if your application uses too few
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mutual exclusions (mutexes) to protect access to a large number of resources.
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A large number of threads that share a small number of resources can also
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cause contention between threads in your application.</p>
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</div>
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<div class="section"><p>Contention between threads over resources can cause context switches
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and paging. To reduce contention within your application, you should hold
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locks for the shortest amount of time and try to prevent a single lock from
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being used for two different or unrelated shared resources. </p>
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</div>
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<div class="section"><p>Threads that poll or spin to wait
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for resources prevent scaling. This form of contention can drastically affect
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the performance of your application. Polling or spinning can also adversely
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affect other threads or jobs, degrading system performance. Use condition
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variables, semaphores, mutexes, or other synchronization primitives so that
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threads never need to poll or spin to wait for resources to become available.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahwpcoco.htm" title="There are several performance considerations for multithreaded jobs on i5/OS.">Performance considerations in multithreaded applications</a></div>
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