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<title>Random boosting</title>
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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Random boosting</span></span>
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<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p><b>Random boosting</b> is a strategy used by the <a href="Scheduling_(computing)" title="Scheduling (computing)">scheduler</a> in <a href="Microsoft_Windows" title="Microsoft Windows">Microsoft Windows</a> to avoid <a href="Deadlock_(computer_science)" title="Deadlock (computer science)">deadlock</a> due to <a href="Priority_inversion" title="Priority inversion">priority inversion</a>. Ready threads holding locks are randomly boosted in priority and allowed to run long enough to exit the critical section. If the thread doesn't get enough time to release the lock, it will get another chance.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>
</p><p>This strategy is no longer used in the latest versions of Windows and has been replaced by a strategy called AutoBoost.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>
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<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
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</style><cite class="citation cs2"><a rel="nofollow" class="external text" href="http://msdn.microsoft.com/en-us/library/windows/desktop/ms684831(v=vs.85).aspx"><i>Priority Inversion (Windows)</i></a>, <a href="Microsoft" title="Microsoft">Microsoft</a><span class="reference-accessdate">, retrieved <span class="nowrap">December 12,</span> 2012</span>, <q>The scheduler solves this problem by randomly boosting the priority of the ready threads (in this case, the low priority lock-holders). The low priority threads run long enough to exit the critical section, and the high-priority thread can enter the critical section. If the low-priority thread does not get enough CPU time to exit the critical section the first time, it will get another chance during the next round of scheduling.</q></cite></span>
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<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite id="CITEREFCohenWoodring1998" class="citation cs2">Cohen, Aaron; Woodring, Mike (1998), <i>Win32 Multithreaded Programming</i>, O'Reilly & Associates, p. 30, <q>Windows NT solves the priority inversion problem by randomly boosting the dynamic priorities of threads that are ready to run.</q></cite></span>
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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://learn.microsoft.com/en-us/windows/win32/procthread/priority-inversion">"Priority Inversion (Windows)"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">12 October</span> 2024</span>. <q>The thread scheduler addresses this issue through a feature called AutoBoost. AutoBoost automatically tracks resource reservations and adjusts thread priorities by applying priority floors that a thread must never fall below. For example, if a low–priority thread acquires a critical section and a higher–priority thread is blocked waiting for the critical section, the priority of the owner is raised to the maximum priority of the waiter until it releases the resource.</q></cite></span>
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