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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="Yields execution back to the Tokio runtime."><title>yield_now in actix_rt::task - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-b778ab399e080a4b.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="actix_rt" data-themes="" data-resource-suffix="" data-rustdoc-version="1.83.0-nightly (7608018cb 2024-09-29)" data-channel="nightly" data-search-js="search-e056c65ede92db13.js" data-settings-js="settings-805db61a62df4bd2.js" ><script src="../../static.files/storage-1d39b6787ed640ff.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../static.files/main-54bc299d2a5e4e43.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-0111fcff984fae8f.css"></noscript><link rel="icon" href="https://actix.rs/favicon.ico"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle" title="show sidebar"></button><a class="logo-container" href="../../actix_rt/index.html"><img src="https://actix.rs/img/logo.png" alt=""></a></nav><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../../actix_rt/index.html"><img src="https://actix.rs/img/logo.png" alt="logo"></a><h2><a href="../../actix_rt/index.html">actix_<wbr>rt</a><span class="version">2.10.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">yield_<wbr>now</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#non-guarantees" title="Non-guarantees">Non-guarantees</a></li></ul></section><div id="rustdoc-modnav"><h2><a href="index.html">In actix_<wbr>rt::<wbr>task</a></h2></div></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><span class="rustdoc-breadcrumbs"><a href="../index.html">actix_rt</a>::<wbr><a href="index.html">task</a></span><h1>Function <span class="fn">yield_now</span><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"></span></div><pre class="rust item-decl"><code>pub async fn yield_now()</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Yields execution back to the Tokio runtime.</p>
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<p>A task yields by awaiting on <code>yield_now()</code>, and may resume when that future
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completes (with no output.) The current task will be re-added as a pending
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task at the <em>back</em> of the pending queue. Any other pending tasks will be
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scheduled. No other waking is required for the task to continue.</p>
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<p>See also the usage example in the <a href="index.html#yield_now">task module</a>.</p>
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<h3 id="non-guarantees"><a class="doc-anchor" href="#non-guarantees">§</a>Non-guarantees</h3>
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<p>This function may not yield all the way up to the executor if there are any
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special combinators above it in the call stack. For example, if a
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<a href="macro@crate::select"><code>tokio::select!</code></a> has another branch complete during the same poll as the
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<code>yield_now()</code>, then the yield is not propagated all the way up to the
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runtime.</p>
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<p>It is generally not guaranteed that the runtime behaves like you expect it
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to when deciding which task to schedule next after a call to <code>yield_now()</code>.
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In particular, the runtime may choose to poll the task that just ran
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<code>yield_now()</code> again immediately without polling any other tasks first. For
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example, the runtime will not drive the IO driver between every poll of a
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task, and this could result in the runtime polling the current task again
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immediately even if there is another task that could make progress if that
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other task is waiting for a notification from the IO driver.</p>
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<p>In general, changes to the order in which the runtime polls tasks is not
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considered a breaking change, and your program should be correct no matter
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which order the runtime polls your tasks in.</p>
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</div></details></section></div></main></body></html>
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