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1 line
14 KiB
JavaScript
1 line
14 KiB
JavaScript
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"use strict";(self.webpackChunkspeice_io=self.webpackChunkspeice_io||[]).push([["4760"],{3643:function(e,t,n){n.r(t),n.d(t,{assets:function(){return c},contentTitle:function(){return o},default:function(){return d},frontMatter:function(){return r},metadata:function(){return a},toc:function(){return l}});var a=n(4111),s=n(5893),i=n(65);let r={slug:"2018/10/case-study-optimization",title:"A case study in heaptrack",date:new Date("2018-10-08T12:00:00.000Z"),authors:["bspeice"],tags:[]},o=void 0,c={authorsImageUrls:[void 0]},l=[{value:"Curiosity",id:"curiosity",level:2},{value:"Turning on the System Allocator",id:"turning-on-the-system-allocator",level:2},{value:"Running heaptrack",id:"running-heaptrack",level:2},{value:"Reading Flamegraphs",id:"reading-flamegraphs",level:2},{value:"Optimizing dtparse",id:"optimizing-dtparse",level:2},{value:"Conclusion",id:"conclusion",level:2}];function h(e){let t={a:"a",blockquote:"blockquote",code:"code",em:"em",h2:"h2",hr:"hr",img:"img",p:"p",pre:"pre",strong:"strong",...(0,i.a)(),...e.components};return(0,s.jsxs)(s.Fragment,{children:[(0,s.jsx)(t.p,{children:"I remember early in my career someone joking that:"}),"\n",(0,s.jsxs)(t.blockquote,{children:["\n",(0,s.jsx)(t.p,{children:"Programmers have it too easy these days. They should learn to develop in low memory environments\nand be more efficient."}),"\n"]}),"\n",(0,s.jsxs)(t.p,{children:["...though it's not like the first code I wrote was for a\n",(0,s.jsx)(t.a,{href:"https://web.archive.org/web/20180924060530/https://education.ti.com/en/products/calculators/graphing-calculators/ti-84-plus-se",children:"graphing calculator"}),"\npacking a whole 24KB of RAM."]}),"\n",(0,s.jsxs)(t.p,{children:["But the principle remains: be efficient with the resources you have, because\n",(0,s.jsx)(t.a,{href:"http://exo-blog.blogspot.com/2007/09/what-intel-giveth-microsoft-taketh-away.html",children:"what Intel giveth, Microsoft taketh away"}),"."]}),"\n",(0,s.jsxs)(t.p,{children:["My professional work is focused on this kind of efficiency; low-latency financial markets demand\nthat you understand at a deep level ",(0,s.jsx)(t.em,{children:"exactly"})," what your code is doing. As I continue experimenting\nwith Rust for personal projects, it's exciting to bring a utilitarian mindset with me: there's\nflexibility for the times I pretend to have a garbage collector, and flexibility for the times that\nI really care about how memory is used."]}),"\n",(0,s.jsx)(t.p,{children:"This post is a (small) case study in how I went from the former to the latter. And ultimately, it's\nintended to be a starting toolkit to empower analysis of your own code."}),"\n",(0,s.jsx)(t.h2,{id:"curiosity",children:"Curiosity"}),"\n",(0,s.jsxs)(t.p,{children:["When I first started building the ",(0,s.jsx)(t.a,{href:"https://crates.io/crates/dtparse",children:"dtparse"})," crate, my intention was to mirror as closely as possible\nthe equivalent ",(0,s.jsx)(t.a,{href:"https://github.com/dateutil/dateutil",children:"Python library"}),". Python, as you may know, is garbage collected. Very\nrarely is memory usage considered in Python, and I likewise wasn't paying too much attention when\n",(0,s.jsx)(t.code,{children:"dtparse"})," was first being built."]}),"\n",(0,s.jsxs)(t.p,{children:["This lackadaisical approach to memory works well enough, and I'm not planning on making ",(0,s.jsx)(t.code,{children:"dtparse"}),'\nhyper-efficient. But every so often, I\'ve wondered: "what exactly is going on in memory?" With the\nadvent of Rust 1.28 and the\n',(0,s.jsx)(t.a,{href:"https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html",children:"Global Allocator trait"}),", I had a really\ngreat idea: ",(0,s.jsx)(t.em,{children:"build a custom allocator that allows you to track your own allocations."})," That way, you\ncan do things like writing tests for both correct results and correct memory usage. I gave it a\n",(0,s.jsx)(t.a,{href:"https://crates.io/crates/qadapt",children:"shot"}),", but learned very quickly: ",(0,s.jsx)(t.strong,{children:"never write your own allocator"}),'. It went
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