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<!doctype html><html lang=en dir=ltr class="blog-wrapper blog-post-page plugin-blog plugin-id-default" data-has-hydrated=false><meta charset=UTF-8><meta name=generator content="Docusaurus v3.6.0"><title data-rh=true>Allocations in Rust: Summary | The Old Speice Guy</title><meta data-rh=true name=viewport content="width=device-width,initial-scale=1.0"><meta data-rh=true name=twitter:card content=summary_large_image><meta data-rh=true property=og:url content=https://speice.io/2019/02/summary><meta data-rh=true property=og:locale content=en><meta data-rh=true name=docusaurus_locale content=en><meta data-rh=true name=docusaurus_tag content=default><meta data-rh=true name=docsearch:language content=en><meta data-rh=true name=docsearch:docusaurus_tag content=default><meta data-rh=true property=og:title content="Allocations in Rust: Summary | The Old Speice Guy"><meta data-rh=true name=description content="While there's a lot of interesting detail captured in this series, it's often helpful to have a"><meta data-rh=true property=og:description content="While there's a lot of interesting detail captured in this series, it's often helpful to have a"><meta data-rh=true property=og:type content=article><meta data-rh=true property=article:published_time content=2019-02-09T12:00:00.000Z><link data-rh=true rel=icon href=/img/favicon.ico><link data-rh=true rel=canonical href=https://speice.io/2019/02/summary><link data-rh=true rel=alternate href=https://speice.io/2019/02/summary hreflang=en><link data-rh=true rel=alternate href=https://speice.io/2019/02/summary hreflang=x-default><script data-rh=true type=application/ld+json>{"@context":"https://schema.org","@id":"https://speice.io/2019/02/summary","@type":"BlogPosting","author":{"@type":"Person","name":"Bradlee Speice"},"dateModified":"2024-11-10T02:05:00.000Z","datePublished":"2019-02-09T12:00:00.000Z","description":"While there's a lot of interesting detail captured in this series, it's often helpful to have a","headline":"Allocations in Rust: Summary","isPartOf":{"@id":"https://speice.io/","@type":"Blog","name":"Blog"},"keywords":[],"mainEntityOfPage":"https://speice.io/2019/02/summary","name":"Allocations in Rust: Summary","url":"https://speice.io/2019/02/summary"}</script><link rel=alternate type=application/rss+xml href=/rss.xml title="The Old Speice Guy RSS Feed"><link rel=alternate type=application/atom+xml href=/atom.xml title="The Old Speice Guy Atom Feed"><link rel=stylesheet href=https://cdn.jsdelivr.net/npm/katex@0.13.24/dist/katex.min.css integrity=sha384-odtC+0UGzzFL/6PNoE8rX/SPcQDXBJ+uRepguP4QkPCm2LBxH3FA3y+fKSiJ+AmM crossorigin><link rel=stylesheet href=/assets/css/styles.ae6ff4a3.css><script src=/assets/js/runtime~main.751b419d.js defer></script><script src=/assets/js/main.62ce6156.js defer></script><body class=navigation-with-keyboard><script>!function(){var t,e=function(){try{return new URLSearchParams(window.location.search).get("docusaurus-theme")}catch(t){}}()||function(){try{return window.localStorage.getItem("theme")}catch(t){}}();t=null!==e?e:"light",document.documentElement.setAttribute("data-theme",t)}(),function(){try{for(var[t,e]of new URLSearchParams(window.location.search).entries())if(t.startsWith("docusaurus-data-")){var a=t.replace("docusaurus-data-","data-");document.documentElement.setAttribute(a,e)}}catch(t){}}()</script><div id=__docusaurus><div role=region aria-label="Skip to main content"><a class=skipToContent_fXgn href=#__docusaurus_skipToContent_fallback>Skip to main content</a></div><nav aria-label=Main class="navbar navbar--fixed-top"><div class=navbar__inner><div class=navbar__items><button aria-label="Toggle navigation bar" aria-expanded=false class="navbar__toggle clean-btn" type=button><svg width=30 height=30 viewBox="0 0 30 30" aria-hidden=true><path stroke=currentColor stroke-linecap=round stroke-miterlimit=10 stroke-width=2 d="M4 7h22M4 15h22M4 23h22"/></svg></button><a class=navbar__brand href=/><div class=navbar__logo><img src=/img/logo.svg alt="Sierpinski Gasket" class="themedComponent_mlkZ themedComponent--light_NVdE"><img src=
document that answers some "yes/no" questions. You may not care about what an <code>Iterator</code> looks like
in assembly, you just need to know whether it allocates an object on the heap or not. And while Rust
will prioritize the fastest behavior it can, here are the rules for each memory type:</p>
<p><strong>Global Allocation</strong>:</p>
<ul>
<li><code>const</code> is a fixed value; the compiler is allowed to copy it wherever useful.</li>
<li><code>static</code> is a fixed reference; the compiler will guarantee it is unique.</li>
</ul>
<p><strong>Stack Allocation</strong>:</p>
<ul>
<li>Everything not using a smart pointer will be allocated on the stack.</li>
<li>Structs, enums, iterators, arrays, and closures are all stack allocated.</li>
<li>Cell types (<code>RefCell</code>) behave like smart pointers, but are stack-allocated.</li>
<li>Inlining (<code>#[inline]</code>) will not affect allocation behavior for better or worse.</li>
<li>Types that are marked <code>Copy</code> are guaranteed to have their contents stack-allocated.</li>
</ul>
<p><strong>Heap Allocation</strong>:</p>
<ul>
<li>Smart pointers (<code>Box</code>, <code>Rc</code>, <code>Mutex</code>, etc.) allocate their contents in heap memory.</li>
<li>Collections (<code>HashMap</code>, <code>Vec</code>, <code>String</code>, etc.) allocate their contents in heap memory.</li>
<li>Some smart pointers in the standard library have counterparts in other crates that don't need heap
memory. If possible, use those.</li>
</ul>
<p><img decoding=async loading=lazy alt="Container Sizes in Rust" src=/assets/images/container-size-7fd54cbb2391e3e7310b0424c5f92cc1.svg width=960 height=540 class=img_ev3q></p>
<p>-- <a href="https://docs.google.com/presentation/d/1q-c7UAyrUlM-eZyTo1pd8SZ0qwA_wYxmPZVOQkoDmH4/edit?usp=sharing" target=_blank rel="noopener noreferrer">Raph Levien</a></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Blog post page navigation"><a class="pagination-nav__link pagination-nav__link--prev" href=/2019/02/08/compiler-optimizations><div class=pagination-nav__sublabel>Older post</div><div class=pagination-nav__label>Allocations in Rust: Compiler optimizations</div></a><a class="pagination-nav__link pagination-nav__link--next" href=/2019/05/making-bread><div class=pagination-nav__sublabel>Newer post</div><div class=pagination-nav__label>Making bread</div></a></nav></main></div></div></div><footer class=footer><div class="container container-fluid"><div class="footer__bottom text--center"><div class=footer__copyright>Copyright © 2024 Bradlee Speice</div></div></div></footer></div>
Deploy website - based on 6dcbc1a72c807487794da173fa5948acd8b76f35 2024-11-10 16:43:02 -05:00			<!doctype html><html lang=en dir=ltr class="blog-wrapper blog-post-page plugin-blog plugin-id-default" data-has-hydrated=false><meta charset=UTF-8><meta name=generator content="Docusaurus v3.6.0"><title data-rh=true>Allocations in Rust: Summary \| The Old Speice Guy</title><meta data-rh=true name=viewport content="width=device-width,initial-scale=1.0"><meta data-rh=true name=twitter:card content=summary_large_image><meta data-rh=true property=og:url content=https://speice.io/2019/02/summary><meta data-rh=true property=og:locale content=en><meta data-rh=true name=docusaurus_locale content=en><meta data-rh=true name=docusaurus_tag content=default><meta data-rh=true name=docsearch:language content=en><meta data-rh=true name=docsearch:docusaurus_tag content=default><meta data-rh=true property=og:title content="Allocations in Rust: Summary \| The Old Speice Guy"><meta data-rh=true name=description content="While there's a lot of interesting detail captured in this series, it's often helpful to have a"><meta data-rh=true property=og:description content="While there's a lot of interesting detail captured in this series, it's often helpful to have a"><meta data-rh=true property=og:type content=article><meta data-rh=true property=article:published_time content=2019-02-09T12:00:00.000Z><link data-rh=true rel=icon href=/img/favicon.ico><link data-rh=true rel=canonical href=https://speice.io/2019/02/summary><link data-rh=true rel=alternate href=https://speice.io/2019/02/summary hreflang=en><link data-rh=true rel=alternate href=https://speice.io/2019/02/summary hreflang=x-default><script data-rh=true type=application/ld+json>{"@context":"https://schema.org","@id":"https://speice.io/2019/02/summary","@type":"BlogPosting","author":{"@type":"Person","name":"Bradlee Speice"},"dateModified":"2024-11-10T02:05:00.000Z","datePublished":"2019-02-09T12:00:00.000Z","description":"While there's a lot of interesting detail captured in this series, it's often helpful to have a","headline":"Allocations in Rust: Summary","isPartOf":{"@id":"https://speice.io/","@type":"Blog","name":"Blog"},"keywords":[],"mainEntityOfPage":"https://speice.io/2019/02/summary","name":"Allocations in Rust: Summary","url":"https://speice.io/2019/02/summary"}</script><link rel=alternate type=application/rss+xml href=/rss.xml title="The Old Speice Guy RSS Feed"><link rel=alternate type=application/atom+xml href=/atom.xml title="The Old Speice Guy Atom Feed"><link rel=stylesheet href=https://cdn.jsdelivr.net/npm/katex@0.13.24/dist/katex.min.css integrity=sha384-odtC+0UGzzFL/6PNoE8rX/SPcQDXBJ+uRepguP4QkPCm2LBxH3FA3y+fKSiJ+AmM crossorigin><link rel=stylesheet href=/assets/css/styles.ae6ff4a3.css><script src=/assets/js/runtime~main.751b419d.js defer></script><script src=/assets/js/main.62ce6156.js defer></script><body class=navigation-with-keyboard><script>!function(){var t,e=function(){try{return new URLSearchParams(window.location.search).get("docusaurus-theme")}catch(t){}}()\|\|function(){try{return window.localStorage.getItem("theme")}catch(t){}}();t=null!==e?e:"light",document.documentElement.setAttribute("data-theme",t)}(),function(){try{for(var[t,e]of new URLSearchParams(window.location.search).entries())if(t.startsWith("docusaurus-data-")){var a=t.replace("docusaurus-data-","data-");document.documentElement.setAttribute(a,e)}}catch(t){}}()</script><div id=__docusaurus><div role=region aria-label="Skip to main content"><a class=skipToContent_fXgn href=#__docusaurus_skipToContent_fallback>Skip to main content</a></div><nav aria-label=Main class="navbar navbar--fixed-top"><div class=navbar__inner><div class=navbar__items><button aria-label="Toggle navigation bar" aria-expanded=false class="navbar__toggle clean-btn" type=button><svg width=30 height=30 viewBox="0 0 30 30" aria-hidden=true><path stroke=currentColor stroke-linecap=round stroke-miterlimit=10 stroke-width=2 d="M4 7h22M4 15h22M4 23h22"/></svg></button><a class=navbar__brand href=/><div class=navbar__logo><img src=/img/logo.svg alt="Sierpinski Gasket" class="themedComponent_mlkZ themedComponent--light_NVdE"><img src=
			`document that answers some "yes/no" questions. You may not care about what an <code>Iterator</code> looks like`
			`in assembly, you just need to know whether it allocates an object on the heap or not. And while Rust`
			`will prioritize the fastest behavior it can, here are the rules for each memory type:</p>`
			`<p><strong>Global Allocation</strong>:</p>`
			`<ul>`
			`<li><code>const</code> is a fixed value; the compiler is allowed to copy it wherever useful.</li>`
			`<li><code>static</code> is a fixed reference; the compiler will guarantee it is unique.</li>`
			`</ul>`
			`<p><strong>Stack Allocation</strong>:</p>`
			`<ul>`
			`<li>Everything not using a smart pointer will be allocated on the stack.</li>`
			`<li>Structs, enums, iterators, arrays, and closures are all stack allocated.</li>`
			`<li>Cell types (<code>RefCell</code>) behave like smart pointers, but are stack-allocated.</li>`
			`<li>Inlining (<code>#[inline]</code>) will not affect allocation behavior for better or worse.</li>`
			`<li>Types that are marked <code>Copy</code> are guaranteed to have their contents stack-allocated.</li>`
			`</ul>`
			`<p><strong>Heap Allocation</strong>:</p>`
			`<ul>`
			`<li>Smart pointers (<code>Box</code>, <code>Rc</code>, <code>Mutex</code>, etc.) allocate their contents in heap memory.</li>`
			`<li>Collections (<code>HashMap</code>, <code>Vec</code>, <code>String</code>, etc.) allocate their contents in heap memory.</li>`
			`<li>Some smart pointers in the standard library have counterparts in other crates that don't need heap`
			`memory. If possible, use those.</li>`
			`</ul>`
			`<p><img decoding=async loading=lazy alt="Container Sizes in Rust" src=/assets/images/container-size-7fd54cbb2391e3e7310b0424c5f92cc1.svg width=960 height=540 class=img_ev3q></p>`
			<p>-- <a href="https://docs.google.com/presentation/d/1q-c7UAyrUlM-eZyTo1pd8SZ0qwA_wYxmPZVOQkoDmH4/edit?usp=sharing" target=_blank rel="noopener noreferrer">Raph Levien</a></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Blog post page navigation"><a class="pagination-nav__link pagination-nav__link--prev" href=/2019/02/08/compiler-optimizations><div class=pagination-nav__sublabel>Older post</div><div class=pagination-nav__label>Allocations in Rust: Compiler optimizations</div></a><a class="pagination-nav__link pagination-nav__link--next" href=/2019/05/making-bread><div class=pagination-nav__sublabel>Newer post</div><div class=pagination-nav__label>Making bread</div></a></nav></main></div></div></div><footer class=footer><div class="container container-fluid"><div class="footer__bottom text--center"><div class=footer__copyright>Copyright © 2024 Bradlee Speice</div></div></div></footer></div>