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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="A thread pool used to execute functions in parallel."><meta name="keywords" content="rust, rustlang, rust-lang, threadpool"><title>threadpool - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../ayu.css" disabled ><script id="default-settings"></script><script src="../storage.js"></script><script src="../crates.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../favicon.svg">
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<link rel="alternate icon" type="image/png" href="../favicon-32x32.png"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc mod"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu" role="button">☰</div><a href='../threadpool/index.html'><div class='logo-container rust-logo'><img src='../rust-logo.png' alt='logo'></div></a><p class="location">Crate threadpool</p><div class="block version"><p>Version 1.8.1</p></div><div class="sidebar-elems"><a id="all-types" href="all.html"><p>See all threadpool's items</p></a><div class="block items"><ul><li><a href="#structs">Structs</a></li></ul></div><p class="location"></p><div id="sidebar-vars" data-name="threadpool" data-ty="mod" data-relpath="../"></div></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu"><img src="../brush.svg" width="18" height="18" alt="Pick another theme!"></button><div id="theme-choices" role="menu"></div></div><nav class="sub"><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><button type="button" class="help-button">?</button>
<a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" height="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class="fqn"><span class="in-band">Crate <a class="mod" href="">threadpool</a></span><span class="out-of-band"><span id="render-detail"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span><a class="srclink" href="../src/threadpool/lib.rs.html#11-1329" title="goto source code">[src]</a></span></h1><div class="docblock"><p>A thread pool used to execute functions in parallel.</p>
<p>Spawns a specified number of worker threads and replenishes the pool if any worker threads
panic.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1><h2 id="synchronized-with-a-channel" class="section-header"><a href="#synchronized-with-a-channel">Synchronized with a channel</a></h2>
<p>Every thread sends one message over the channel, which then is collected with the <code>take()</code>.</p>
<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">threadpool</span>::<span class="ident">ThreadPool</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::<span class="ident">mpsc</span>::<span class="ident">channel</span>;
<span class="kw">let</span> <span class="ident">n_workers</span> <span class="op">=</span> <span class="number">4</span>;
<span class="kw">let</span> <span class="ident">n_jobs</span> <span class="op">=</span> <span class="number">8</span>;
<span class="kw">let</span> <span class="ident">pool</span> <span class="op">=</span> <span class="ident">ThreadPool</span>::<span class="ident">new</span>(<span class="ident">n_workers</span>);
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel</span>();
<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">n_jobs</span> {
<span class="kw">let</span> <span class="ident">tx</span> <span class="op">=</span> <span class="ident">tx</span>.<span class="ident">clone</span>();
<span class="ident">pool</span>.<span class="ident">execute</span>(<span class="kw">move</span><span class="op">|</span><span class="op">|</span> {
<span class="ident">tx</span>.<span class="ident">send</span>(<span class="number">1</span>).<span class="ident">expect</span>(<span class="string">"channel will be there waiting for the pool"</span>);
});
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">rx</span>.<span class="ident">iter</span>().<span class="ident">take</span>(<span class="ident">n_jobs</span>).<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">a</span>, <span class="ident">b</span><span class="op">|</span> <span class="ident">a</span> <span class="op">+</span> <span class="ident">b</span>), <span class="number">8</span>);</pre></div>
<h2 id="synchronized-with-a-barrier" class="section-header"><a href="#synchronized-with-a-barrier">Synchronized with a barrier</a></h2>
<p>Keep in mind, if a barrier synchronizes more jobs than you have workers in the pool,
you will end up with a <a href="https://en.wikipedia.org/wiki/Deadlock">deadlock</a>
at the barrier which is <a href="https://doc.rust-lang.org/reference/behavior-not-considered-unsafe.html">not considered unsafe</a>.</p>
<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">threadpool</span>::<span class="ident">ThreadPool</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::{<span class="ident">Arc</span>, <span class="ident">Barrier</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::<span class="ident">atomic</span>::{<span class="ident">AtomicUsize</span>, <span class="ident">Ordering</span>};
<span class="comment">// create at least as many workers as jobs or you will deadlock yourself</span>
<span class="kw">let</span> <span class="ident">n_workers</span> <span class="op">=</span> <span class="number">42</span>;
<span class="kw">let</span> <span class="ident">n_jobs</span> <span class="op">=</span> <span class="number">23</span>;
<span class="kw">let</span> <span class="ident">pool</span> <span class="op">=</span> <span class="ident">ThreadPool</span>::<span class="ident">new</span>(<span class="ident">n_workers</span>);
<span class="kw">let</span> <span class="ident">an_atomic</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">AtomicUsize</span>::<span class="ident">new</span>(<span class="number">0</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">n_jobs</span> <span class="op"><</span><span class="op">=</span> <span class="ident">n_workers</span>, <span class="string">"too many jobs, will deadlock"</span>);
<span class="comment">// create a barrier that waits for all jobs plus the starter thread</span>
<span class="kw">let</span> <span class="ident">barrier</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Barrier</span>::<span class="ident">new</span>(<span class="ident">n_jobs</span> <span class="op">+</span> <span class="number">1</span>));
<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">n_jobs</span> {
<span class="kw">let</span> <span class="ident">barrier</span> <span class="op">=</span> <span class="ident">barrier</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="ident">an_atomic</span> <span class="op">=</span> <span class="ident">an_atomic</span>.<span class="ident">clone</span>();
<span class="ident">pool</span>.<span class="ident">execute</span>(<span class="kw">move</span><span class="op">|</span><span class="op">|</span> {
<span class="comment">// do the heavy work</span>
<span class="ident">an_atomic</span>.<span class="ident">fetch_add</span>(<span class="number">1</span>, <span class="ident">Ordering</span>::<span class="ident">Relaxed</span>);
<span class="comment">// then wait for the other threads</span>
<span class="ident">barrier</span>.<span class="ident">wait</span>();
});
}
<span class="comment">// wait for the threads to finish the work</span>
<span class="ident">barrier</span>.<span class="ident">wait</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">an_atomic</span>.<span class="ident">load</span>(<span class="ident">Ordering</span>::<span class="ident">SeqCst</span>), <span class="comment">/* n_jobs = */</span> <span class="number">23</span>);</pre></div>
</div><h2 id="structs" class="section-header"><a href="#structs">Structs</a></h2>
<table><tr class="module-item"><td><a class="struct" href="struct.Builder.html" title="threadpool::Builder struct">Builder</a></td><td class="docblock-short"><p><a href="struct.ThreadPool.html"><code>ThreadPool</code></a> factory, which can be used in order to configure the properties of the
<a href="struct.ThreadPool.html"><code>ThreadPool</code></a>.</p>
</td></tr><tr class="module-item"><td><a class="struct" href="struct.ThreadPool.html" title="threadpool::ThreadPool struct">ThreadPool</a></td><td class="docblock-short"><p>Abstraction of a thread pool for basic parallelism.</p>
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