mirror of
https://github.com/bspeice/speice.io
synced 2024-12-22 16:48:10 -05:00
92 lines
37 KiB
HTML
92 lines
37 KiB
HTML
<!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 v3.6.1"><title data-rh=true>A case study in heaptrack | 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/2018/10/case-study-optimization><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="A case study in heaptrack | The Old Speice Guy"><meta data-rh=true name=description content="I remember early in my career someone joking that:"><meta data-rh=true property=og:description content="I remember early in my career someone joking that:"><meta data-rh=true property=og:type content=article><meta data-rh=true property=article:published_time content=2018-10-08T12:00:00.000Z><link data-rh=true rel=icon href=/img/favicon.ico><link data-rh=true rel=canonical href=https://speice.io/2018/10/case-study-optimization><link data-rh=true rel=alternate href=https://speice.io/2018/10/case-study-optimization hreflang=en><link data-rh=true rel=alternate href=https://speice.io/2018/10/case-study-optimization hreflang=x-default><script data-rh=true type=application/ld+json>{"@context":"https://schema.org","@id":"https://speice.io/2018/10/case-study-optimization","@type":"BlogPosting","author":{"@type":"Person","name":"Bradlee Speice"},"dateModified":"2024-11-09T22:02:02.000Z","datePublished":"2018-10-08T12:00:00.000Z","description":"I remember early in my career someone joking that:","headline":"A case study in heaptrack","isPartOf":{"@id":"https://speice.io/","@type":"Blog","name":"Blog"},"keywords":[],"mainEntityOfPage":"https://speice.io/2018/10/case-study-optimization","name":"A case study in heaptrack","url":"https://speice.io/2018/10/case-study-optimization"}</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=/katex/katex.min.css><link rel=stylesheet href=/assets/css/styles.16c3428d.css><script src=/assets/js/runtime~main.29a27dcf.js defer></script><script src=/assets/js/main.d461af80.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=/img/logo-dark.svg alt="Sierpinski Gasket" class="themedComponent_mlkZ themedComponent--dark_xIcU"></div><b class="navbar__title text--truncate">The Old Speice Guy</b></a></div><div class="navbar__items navbar__items--right"><a href=https://github.com/bspeice target=_blank rel="noopener noreferrer" class="navbar__item navbar__link header-github-link"></a><div class="toggle_vylO colorModeToggle_DEke"><button class="clean-btn toggleButton_gllP toggleButtonDisabled_aARS" type=button disabled title="Switch between dark and light mode (currently light mode)" aria-label="Switch between dark and light mode (currently light mode)" aria-live=polite aria-pressed=false><svg viewBox="0 0 24 24" width=24 height=24 class=lightToggleIcon_pyhR><path fill=currentColor d="M12,9c1.65,0,3,1.35,3,3s-1.35,3-3,3s-3-1.35-3-3S10.35,9,12,9 M12,7c-2.76,0-5,2.24-5,5s2.24,5,5,5s5-2.24,5-5 S14.76,7,12,7L12,7z M2,13l2,0c0.55,0,1-0.45,1-1s-0.45-1-1-1l-2,0c-0.55,0-1,0.45-1,1S1.45,13,2,13z M20,13l2,0c0.55,0,1-0.45,1-1 s-0.45-1-1-1l-2,0c-0.55,0-1,0.45-1,1S19.45,13,20,13z M11,2v2c0,0.55,0.45,1,1,1s1-0.45,1-1V2c0-0.55-0.45-1-1-1S11,1.45,11,2z M11,20v2c0,0.55,0.45,1,1,1s1-0.45,1-1v-2c0-0.55-0.45-1-1-1C11.45,19,11,19.45,11,20z M5.99,4.58c-0.39-0.39-1.03-0.39-1.41,0 c-0.39,0.39-0.39,1.03,0,1.41l1.06,1.06c0.39,0.39,1.03,0.39,1.41,0s0.39-1.03,0-1.41L5.99,4.58z M18.36,16.95 c-0.39-0.39-1.03-0.39-1.41,0c-0.39,0.39-0.39,1.03,0,1.41l1.06,1.06c0.39,0.39,1.03,0.39,1.41,0c0.39-0.39,0.39-1.03,0-1.41 L18.36,16.95z M19.42,5.99c0.39-0.39,0.39-1.03,0-1.41c-0.39-0.39-1.03-0.39-1.41,0l-1.06,1.06c-0.39,0.39-0.39,1.03,0,1.41 s1.03,0.39,1.41,0L19.42,5.99z M7.05,18.36c0.39-0.39,0.39-1.03,0-1.41c-0.39-0.39-1.03-0.39-1.41,0l-1.06,1.06 c-0.39,0.39-0.39,1.03,0,1.41s1.03,0.39,1.41,0L7.05,18.36z"/></svg><svg viewBox="0 0 24 24" width=24 height=24 class=darkToggleIcon_wfgR><path fill=currentColor d="M9.37,5.51C9.19,6.15,9.1,6.82,9.1,7.5c0,4.08,3.32,7.4,7.4,7.4c0.68,0,1.35-0.09,1.99-0.27C17.45,17.19,14.93,19,12,19 c-3.86,0-7-3.14-7-7C5,9.07,6.81,6.55,9.37,5.51z M12,3c-4.97,0-9,4.03-9,9s4.03,9,9,9s9-4.03,9-9c0-0.46-0.04-0.92-0.1-1.36 c-0.98,1.37-2.58,2.26-4.4,2.26c-2.98,0-5.4-2.42-5.4-5.4c0-1.81,0.89-3.42,2.26-4.4C12.92,3.04,12.46,3,12,3L12,3z"/></svg></button></div><div class=navbarSearchContainer_Bca1><div class=navbar__search><span aria-label="expand searchbar" role=button class=search-icon tabindex=0></span><input id=search_input_react type=search placeholder=Loading... aria-label=Search class="navbar__search-input search-bar" disabled></div></div></div></div><div role=presentation class=navbar-sidebar__backdrop></div></nav><div id=__docusaurus_skipToContent_fallback class="main-wrapper mainWrapper_z2l0"><div class="container margin-vert--lg"><div class=row><aside class="col col--3"><nav class="sidebar_re4s thin-scrollbar" aria-label="Blog recent posts navigation"><div class="sidebarItemTitle_pO2u margin-bottom--md">All posts</div><div role=group><h3>2024</h3><div role=group><h4>Playing with fire</h4><ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2024/11/playing-with-fire>The fractal flame algorithm</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2024/11/playing-with-fire-transforms>Transforms and variations</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2024/11/playing-with-fire-log-density>Tone mapping and color</a></ul></ul></div></div><div role=group><h3>2022</h3><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2011/11/webpack-industrial-complex>The webpack industrial complex</a></ul></div><div role=group><h3>2019</h3><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/12/release-the-gil>Release the GIL</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/09/binary-format-shootout>Binary format shootout</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/06/high-performance-systems>On building high performance systems</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/05/making-bread>Making bread</a></ul><div role=group><h4>Allocations in Rust</h4><ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/02/understanding-allocations-in-rust>Foreword</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/02/the-whole-world>Global memory</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/02/stacking-up>Fixed memory</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/02/a-heaping-helping>Dynamic memory</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/02/08/compiler-optimizations>Compiler optimizations</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2019/02/summary>Summary</a></ul></ul></div></div><div role=group><h3>2018</h3><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/12/allocation-safety>QADAPT - debug_assert! for allocations</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/12/what-small-business-really-means>More "what companies really mean"</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a aria-current=page class="sidebarItemLink_mo7H sidebarItemLinkActive_I1ZP" href=/2018/10/case-study-optimization>A case study in heaptrack</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/09/isomorphic-apps>Isomorphic desktop apps with Rust</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/09/primitives-in-rust-are-weird>Primitives in Rust are weird (and cool)</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/06/dateutil-parser-to-rust>What I learned porting dateutil to Rust</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/05/hello>Hello!</a></ul><div role=group><h4>Captain's Cookbook</h4><ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/01/captains-cookbook-part-1>Project setup</a><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2018/01/captains-cookbook-part-2>Practical usage</a></ul></ul></div></div><div role=group><h3>2016</h3><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/11/pca-audio-compression>PCA audio compression</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/10/rustic-repodcasting>A Rustic re-podcasting server</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/06/event-studies-and-earnings-releases>Event studies and earnings releases</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/05/the-unfair-casino>The unfair casino</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/04/tick-tock>Tick tock...</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/03/tweet-like-me>Tweet like me</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/03/predicting-santander-customer-happiness>Predicting Santander customer happiness</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/02/profitability-using-the-investment-formula>Profitability using the investment formula</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/02/guaranteed-money-maker>Guaranteed money maker</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/01/cloudy-in-seattle>Cloudy in Seattle</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2016/01/complaining-about-the-weather>Complaining about the weather</a></ul></div><div role=group><h3>2015</h3><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2015/12/testing-cramer>Testing Cramer</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2015/11/autocallable>Autocallable Bonds</a></ul><ul class="sidebarItemList_Yudw clean-list"><li class=sidebarItem__DBe><a class=sidebarItemLink_mo7H href=/2015/11/welcome>Welcome, and an algorithm</a></ul></div></nav></aside><main class="col col--7"><article><header><h1 class=title_f1Hy>A case study in heaptrack</h1><div class="container_mt6G margin-vert--md"><time datetime=2018-10-08T12:00:00.000Z>October 8, 2018</time> · <!-- -->5 min read</div><div class="margin-top--md margin-bottom--sm row"><div class="col col--12 authorCol_Hf19"><div class="avatar margin-bottom--sm"><div class="avatar__intro authorDetails_lV9A"><div class=avatar__name><span class=authorName_yefp>Bradlee Speice</span></div><div class=authorSocials_rSDt><a href=https://github.com/bspeice target=_blank rel="noopener noreferrer" class=authorSocialLink_owbf title=GitHub><svg viewBox="0 0 256 250" width=1em height=1em class="authorSocialLink_owbf githubSvg_Uu4N" style=--dark:#000;--light:#fff preserveAspectRatio=xMidYMid><path d="M128.001 0C57.317 0 0 57.307 0 128.001c0 56.554 36.676 104.535 87.535 121.46 6.397 1.185 8.746-2.777 8.746-6.158 0-3.052-.12-13.135-.174-23.83-35.61 7.742-43.124-15.103-43.124-15.103-5.823-14.795-14.213-18.73-14.213-18.73-11.613-7.944.876-7.78.876-7.78 12.853.902 19.621 13.19 19.621 13.19 11.417 19.568 29.945 13.911 37.249 10.64 1.149-8.272 4.466-13.92 8.127-17.116-28.431-3.236-58.318-14.212-58.318-63.258 0-13.975 5-25.394 13.188-34.358-1.329-3.224-5.71-16.242 1.24-33.874 0 0 10.749-3.44 35.21 13.121 10.21-2.836 21.16-4.258 32.038-4.307 10.878.049 21.837 1.47 32.066 4.307 24.431-16.56 35.165-13.12 35.165-13.12 6.967 17.63 2.584 30.65 1.255 33.873 8.207 8.964 13.173 20.383 13.173 34.358 0 49.163-29.944 59.988-58.447 63.157 4.591 3.972 8.682 11.762 8.682 23.704 0 17.126-.148 30.91-.148 35.126 0 3.407 2.304 7.398 8.792 6.14C219.37 232.5 256 184.537 256 128.002 256 57.307 198.691 0 128.001 0Zm-80.06 182.34c-.282.636-1.283.827-2.194.39-.929-.417-1.45-1.284-1.15-1.922.276-.655 1.279-.838 2.205-.399.93.418 1.46 1.293 1.139 1.931Zm6.296 5.618c-.61.566-1.804.303-2.614-.591-.837-.892-.994-2.086-.375-2.66.63-.566 1.787-.301 2.626.591.838.903 1 2.088.363 2.66Zm4.32 7.188c-.785.545-2.067.034-2.86-1.104-.784-1.138-.784-2.503.017-3.05.795-.547 2.058-.055 2.861 1.075.782 1.157.782 2.522-.019 3.08Zm7.304 8.325c-.701.774-2.196.566-3.29-.49-1.119-1.032-1.43-2.496-.726-3.27.71-.776 2.213-.558 3.315.49 1.11 1.03 1.45 2.505.701 3.27Zm9.442 2.81c-.31 1.003-1.75 1.459-3.199 1.033-1.448-.439-2.395-1.613-2.103-2.626.301-1.01 1.747-1.484 3.207-1.028 1.446.436 2.396 1.602 2.095 2.622Zm10.744 1.193c.036 1.055-1.193 1.93-2.715 1.95-1.53.034-2.769-.82-2.786-1.86 0-1.065 1.202-1.932 2.733-1.958 1.522-.03 2.768.818 2.768 1.868Zm10.555-.405c.182 1.03-.875 2.088-2.387 2.37-1.485.271-2.861-.365-3.05-1.386-.184-1.056.893-2.114 2.376-2.387 1.514-.263 2.868.356 3.061 1.403Z"/></svg></a></div></div></div></div></div></header><div id=__blog-post-container class=markdown><p>I remember early in my career someone joking that:</p>
|
||
<blockquote>
|
||
<p>Programmers have it too easy these days. They should learn to develop in low memory environments
|
||
and be more efficient.</p>
|
||
</blockquote>
|
||
<p>...though it's not like the first code I wrote was for a
|
||
<a href=https://web.archive.org/web/20180924060530/https://education.ti.com/en/products/calculators/graphing-calculators/ti-84-plus-se target=_blank rel="noopener noreferrer">graphing calculator</a>
|
||
packing a whole 24KB of RAM.</p>
|
||
<p>But the principle remains: be efficient with the resources you have, because
|
||
<a href=http://exo-blog.blogspot.com/2007/09/what-intel-giveth-microsoft-taketh-away.html target=_blank rel="noopener noreferrer">what Intel giveth, Microsoft taketh away</a>.</p>
|
||
<p>My professional work is focused on this kind of efficiency; low-latency financial markets demand
|
||
that you understand at a deep level <em>exactly</em> what your code is doing. As I continue experimenting
|
||
with Rust for personal projects, it's exciting to bring a utilitarian mindset with me: there's
|
||
flexibility for the times I pretend to have a garbage collector, and flexibility for the times that
|
||
I really care about how memory is used.</p>
|
||
<p>This post is a (small) case study in how I went from the former to the latter. And ultimately, it's
|
||
intended to be a starting toolkit to empower analysis of your own code.</p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id=curiosity>Curiosity<a href=#curiosity class=hash-link aria-label="Direct link to Curiosity" title="Direct link to Curiosity"></a></h2>
|
||
<p>When I first started building the <a href=https://crates.io/crates/dtparse target=_blank rel="noopener noreferrer">dtparse</a> crate, my intention was to mirror as closely as possible
|
||
the equivalent <a href=https://github.com/dateutil/dateutil target=_blank rel="noopener noreferrer">Python library</a>. Python, as you may know, is garbage collected. Very
|
||
rarely is memory usage considered in Python, and I likewise wasn't paying too much attention when
|
||
<code>dtparse</code> was first being built.</p>
|
||
<p>This lackadaisical approach to memory works well enough, and I'm not planning on making <code>dtparse</code>
|
||
hyper-efficient. But every so often, I've wondered: "what exactly is going on in memory?" With the
|
||
advent of Rust 1.28 and the
|
||
<a href=https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html target=_blank rel="noopener noreferrer">Global Allocator trait</a>, I had a really
|
||
great idea: <em>build a custom allocator that allows you to track your own allocations.</em> That way, you
|
||
can do things like writing tests for both correct results and correct memory usage. I gave it a
|
||
<a href=https://crates.io/crates/qadapt target=_blank rel="noopener noreferrer">shot</a>, but learned very quickly: <strong>never write your own allocator</strong>. It went from "fun
|
||
weekend project" to "I have literally no idea what my computer is doing" at breakneck speed.</p>
|
||
<p>Instead, I'll highlight a separate path I took to make sense of my memory usage: <a href=https://github.com/KDE/heaptrack target=_blank rel="noopener noreferrer">heaptrack</a>.</p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id=turning-on-the-system-allocator>Turning on the System Allocator<a href=#turning-on-the-system-allocator class=hash-link aria-label="Direct link to Turning on the System Allocator" title="Direct link to Turning on the System Allocator"></a></h2>
|
||
<p>This is the hardest part of the post. Because Rust uses
|
||
<a href=https://github.com/rust-lang/rust/pull/27400#issue-41256384 target=_blank rel="noopener noreferrer">its own allocator</a> by default,
|
||
<code>heaptrack</code> is unable to properly record unmodified Rust code. To remedy this, we'll make use of the
|
||
<code>#[global_allocator]</code> attribute.</p>
|
||
<p>Specifically, in <code>lib.rs</code> or <code>main.rs</code>, add this:</p>
|
||
<div class="language-rust codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class=codeBlockContent_biex><pre tabindex=0 class="prism-code language-rust codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class=codeBlockLines_e6Vv><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token keyword" style="color:hsl(301, 63%, 40%)">use</span><span class="token plain"> </span><span class="token namespace">std</span><span class="token namespace punctuation" style="color:hsl(119, 34%, 47%)">::</span><span class="token namespace">alloc</span><span class="token namespace punctuation" style="color:hsl(119, 34%, 47%)">::</span><span class="token class-name" style="color:hsl(35, 99%, 36%)">System</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">;</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain" style=display:inline-block></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"></span><span class="token attribute attr-name" style="color:hsl(35, 99%, 36%)">#[global_allocator]</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"></span><span class="token keyword" style="color:hsl(301, 63%, 40%)">static</span><span class="token plain"> </span><span class="token constant" style="color:hsl(35, 99%, 36%)">GLOBAL</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">:</span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">System</span><span class="token plain"> </span><span class="token operator" style="color:hsl(221, 87%, 60%)">=</span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">System</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">;</span><br></span></code></pre><div class=buttonGroup__atx><button type=button aria-label="Copy code to clipboard" title=Copy class=clean-btn><span class=copyButtonIcons_eSgA aria-hidden=true><svg viewBox="0 0 24 24" class=copyButtonIcon_y97N><path fill=currentColor d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"/></svg><svg viewBox="0 0 24 24" class=copyButtonSuccessIcon_LjdS><path fill=currentColor d=M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z /></svg></span></button></div></div></div>
|
||
<p>...and that's it. Everything else comes essentially for free.</p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id=running-heaptrack>Running heaptrack<a href=#running-heaptrack class=hash-link aria-label="Direct link to Running heaptrack" title="Direct link to Running heaptrack"></a></h2>
|
||
<p>Assuming you've installed heaptrack <small>(Homebrew in Mac, package manager
|
||
in Linux, ??? in Windows)</small>, all that's left is to fire up your application:</p>
|
||
<div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class=codeBlockContent_biex><pre tabindex=0 class="prism-code language-text codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class=codeBlockLines_e6Vv><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain">heaptrack my_application</span><br></span></code></pre><div class=buttonGroup__atx><button type=button aria-label="Copy code to clipboard" title=Copy class=clean-btn><span class=copyButtonIcons_eSgA aria-hidden=true><svg viewBox="0 0 24 24" class=copyButtonIcon_y97N><path fill=currentColor d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"/></svg><svg viewBox="0 0 24 24" class=copyButtonSuccessIcon_LjdS><path fill=currentColor d=M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z /></svg></span></button></div></div></div>
|
||
<p>It's that easy. After the program finishes, you'll see a file in your local directory with a name
|
||
like <code>heaptrack.my_appplication.XXXX.gz</code>. If you load that up in <code>heaptrack_gui</code>, you'll see
|
||
something like this:</p>
|
||
<p><img decoding=async loading=lazy alt=heaptrack src=/assets/images/heaptrack-before-11fba190f97831448cc539ebb32fa579.png width=1312 height=320 class=img_ev3q></p>
|
||
<hr>
|
||
<p>And even these pretty colors:</p>
|
||
<p><img decoding=async loading=lazy alt="pretty colors" src=/assets/images/heaptrack-flamegraph-5094664fa79faaf2664b38505c15ac1f.png width=1284 height=715 class=img_ev3q></p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id=reading-flamegraphs>Reading Flamegraphs<a href=#reading-flamegraphs class=hash-link aria-label="Direct link to Reading Flamegraphs" title="Direct link to Reading Flamegraphs"></a></h2>
|
||
<p>To make sense of our memory usage, we're going to focus on that last picture - it's called a
|
||
<a href=http://www.brendangregg.com/flamegraphs.html target=_blank rel="noopener noreferrer">"flamegraph"</a>. These charts are typically used to
|
||
show how much time your program spends executing each function, but they're used here to show how
|
||
much memory was allocated during those functions instead.</p>
|
||
<p>For example, we can see that all executions happened during the <code>main</code> function:</p>
|
||
<p><img decoding=async loading=lazy alt="allocations in main" src=/assets/images/heaptrack-main-colorized-cfe5d7d345d32cfc1a0f297580619718.png width=654 height=343 class=img_ev3q></p>
|
||
<p>...and within that, all allocations happened during <code>dtparse::parse</code>:</p>
|
||
<p><img decoding=async loading=lazy alt="allocations in dtparse" src=/assets/images/heaptrack-dtparse-colorized-e6caf224f50df2dd56981f5b02970325.png width=654 height=315 class=img_ev3q></p>
|
||
<p>...and within <em>that</em>, allocations happened in two different places:</p>
|
||
<p><img decoding=async loading=lazy alt="allocations in parseinfo" src=/assets/images/heaptrack-parseinfo-colorized-a1898beaf28a3997ac86810f872539b7.png width=654 height=372 class=img_ev3q></p>
|
||
<p>Now I apologize that it's hard to see, but there's one area specifically that stuck out as an issue:
|
||
<strong>what the heck is the <code>Default</code> thing doing?</strong></p>
|
||
<p><img decoding=async loading=lazy alt="pretty colors" src=/assets/images/heaptrack-flamegraph-default-26cc411d387f58f50cb548f8e81df1a1.png width=1284 height=715 class=img_ev3q></p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id=optimizing-dtparse>Optimizing dtparse<a href=#optimizing-dtparse class=hash-link aria-label="Direct link to Optimizing dtparse" title="Direct link to Optimizing dtparse"></a></h2>
|
||
<p>See, I knew that there were some allocations during calls to <code>dtparse::parse</code>, but I was totally
|
||
wrong about where the bulk of allocations occurred in my program. Let me post the code and see if
|
||
you can spot the mistake:</p>
|
||
<div class="language-rust codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class=codeBlockContent_biex><pre tabindex=0 class="prism-code language-rust codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class=codeBlockLines_e6Vv><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token comment" style="color:hsl(230, 4%, 64%)">/// Main entry point for using `dtparse`.</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"></span><span class="token keyword" style="color:hsl(301, 63%, 40%)">pub</span><span class="token plain"> </span><span class="token keyword" style="color:hsl(301, 63%, 40%)">fn</span><span class="token plain"> </span><span class="token function-definition function" style="color:hsl(221, 87%, 60%)">parse</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token plain">timestr</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">:</span><span class="token plain"> </span><span class="token operator" style="color:hsl(221, 87%, 60%)">&</span><span class="token keyword" style="color:hsl(301, 63%, 40%)">str</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">-></span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">ParseResult</span><span class="token operator" style="color:hsl(221, 87%, 60%)"><</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token class-name" style="color:hsl(35, 99%, 36%)">NaiveDateTime</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">Option</span><span class="token operator" style="color:hsl(221, 87%, 60%)"><</span><span class="token class-name" style="color:hsl(35, 99%, 36%)">FixedOffset</span><span class="token operator" style="color:hsl(221, 87%, 60%)">></span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token operator" style="color:hsl(221, 87%, 60%)">></span><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">{</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token keyword" style="color:hsl(301, 63%, 40%)">let</span><span class="token plain"> res </span><span class="token operator" style="color:hsl(221, 87%, 60%)">=</span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">Parser</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">::</span><span class="token function" style="color:hsl(221, 87%, 60%)">default</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">.</span><span class="token function" style="color:hsl(221, 87%, 60%)">parse</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"> timestr</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">None</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">None</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> </span><span class="token boolean" style="color:hsl(35, 99%, 36%)">false</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> </span><span class="token boolean" style="color:hsl(35, 99%, 36%)">false</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">None</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> </span><span class="token boolean" style="color:hsl(35, 99%, 36%)">false</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token operator" style="color:hsl(221, 87%, 60%)">&</span><span class="token class-name" style="color:hsl(35, 99%, 36%)">HashMap</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">::</span><span class="token function" style="color:hsl(221, 87%, 60%)">new</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token operator" style="color:hsl(221, 87%, 60%)">?</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">;</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain" style=display:inline-block></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">Ok</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token plain">res</span><span class="token number" style="color:hsl(35, 99%, 36%)">.0</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"> res</span><span class="token number" style="color:hsl(35, 99%, 36%)">.1</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token plain"></span><br></span><span class=token-line style="color:hsl(230, 8%, 24%)"><span class="token plain"></span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">}</span><br></span></code></pre><div class=buttonGroup__atx><button type=button aria-label="Copy code to clipboard" title=Copy class=clean-btn><span class=copyButtonIcons_eSgA aria-hidden=true><svg viewBox="0 0 24 24" class=copyButtonIcon_y97N><path fill=currentColor d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"/></svg><svg viewBox="0 0 24 24" class=copyButtonSuccessIcon_LjdS><path fill=currentColor d=M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z /></svg></span></button></div></div></div>
|
||
<blockquote>
|
||
<p><a href=https://github.com/bspeice/dtparse/blob/4d7c5dd99572823fa4a390b483c38ab020a2172f/src/lib.rs#L1286 target=_blank rel="noopener noreferrer">dtparse</a></p>
|
||
</blockquote>
|
||
<hr>
|
||
<p>Because <code>Parser::parse</code> requires a mutable reference to itself, I have to create a new
|
||
<code>Parser::default</code> every time it receives a string. This is excessive! We'd rather have an immutable
|
||
parser that can be re-used, and avoid allocating memory in the first place.</p>
|
||
<p>Armed with that information, I put some time in to
|
||
<a href=https://github.com/bspeice/dtparse/commit/741afa34517d6bc1155713bbc5d66905fea13fad#diff-b4aea3e418ccdb71239b96952d9cddb6 target=_blank rel="noopener noreferrer">make the parser immutable</a>.
|
||
Now that I can re-use the same parser over and over, the allocations disappear:</p>
|
||
<p><img decoding=async loading=lazy alt="allocations cleaned up" src=/assets/images/heaptrack-flamegraph-after-cedc4c3519313f5af538364165e92c34.png width=1272 height=712 class=img_ev3q></p>
|
||
<p>In total, we went from requiring 2 MB of memory in
|
||
<a href=https://crates.io/crates/dtparse/1.0.2 target=_blank rel="noopener noreferrer">version 1.0.2</a>:</p>
|
||
<p><img decoding=async loading=lazy alt="memory before" src=/assets/images/heaptrack-closeup-12ae3897c033ccb3684a88dd45592e14.png width=717 height=116 class=img_ev3q></p>
|
||
<p>All the way down to 300KB in <a href=https://crates.io/crates/dtparse/1.0.3 target=_blank rel="noopener noreferrer">version 1.0.3</a>:</p>
|
||
<p><img decoding=async loading=lazy alt="memory after" src=/assets/images/heaptrack-closeup-after-967bc4596c480bcc9e8410b0a7a64a00.png width=739 height=123 class=img_ev3q></p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id=conclusion>Conclusion<a href=#conclusion class=hash-link aria-label="Direct link to Conclusion" title="Direct link to Conclusion"></a></h2>
|
||
<p>In the end, you don't need to write a custom allocator to be efficient with memory, great tools
|
||
already exist to help you understand what your program is doing.</p>
|
||
<p><strong>Use them.</strong></p>
|
||
<p>Given that <a href=https://en.wikipedia.org/wiki/Moore%27s_law target=_blank rel="noopener noreferrer">Moore's Law</a> is
|
||
<a href=https://www.technologyreview.com/s/601441/moores-law-is-dead-now-what/ target=_blank rel="noopener noreferrer">dead</a>, we've all got to do
|
||
our part to take back what Microsoft stole.</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=/2018/09/isomorphic-apps><div class=pagination-nav__sublabel>Older post</div><div class=pagination-nav__label>Isomorphic desktop apps with Rust</div></a><a class="pagination-nav__link pagination-nav__link--next" href=/2018/12/what-small-business-really-means><div class=pagination-nav__sublabel>Newer post</div><div class=pagination-nav__label>More "what companies really mean"</div></a></nav></main><div class="col col--2"><div class="tableOfContents_bqdL thin-scrollbar"><ul class="table-of-contents table-of-contents__left-border"><li><a href=#curiosity class="table-of-contents__link toc-highlight">Curiosity</a><li><a href=#turning-on-the-system-allocator class="table-of-contents__link toc-highlight">Turning on the System Allocator</a><li><a href=#running-heaptrack class="table-of-contents__link toc-highlight">Running heaptrack</a><li><a href=#reading-flamegraphs class="table-of-contents__link toc-highlight">Reading Flamegraphs</a><li><a href=#optimizing-dtparse class="table-of-contents__link toc-highlight">Optimizing dtparse</a><li><a href=#conclusion class="table-of-contents__link toc-highlight">Conclusion</a></ul></div></div></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> |