JavaScript performance is weird... Write scientifically faster code with benchmarking

[@pokefreak2112]

The benchmarks should really also include memory allocations. array map/filter create new a new copy of the array every time so even if they look decent on isolated benchmarks they put load on the GC which may introduce lag spikes if you spam them too much.

[@lbgstzockt8493]

And memory reads. I would rather do ten compares than one RAM read.

[@CTSSTC]

We should just transpile code and let it choose the best for loop :P maybe allow an annotation for expected loop size or even better let the runtime figure it out and optimize over time due to it running its own measurements ;D These are things we shouldn't be worried about when it could potentially be automated. We should instead be focused on conveying expectations.

[@allesarfint]

0:24 "Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%."

[@AbdelhakOussaid]

Shout out to those developers, like me, who write gibberish and it works!

[@ARandomUserOfThisWorld]

I don’t just use a DB… I use an excel spreadsheet, and when it runs of space(which is hardcoded at like 1mil rows), it creates a new spreadsheet with a new ID which is specified in the filename and nowhere else, and use that, all of those files together, instead of a DB. And all of them are .xlsx files btw.

[@vikingthedude]

@@ARandomUserOfThisWorld awesome. I use fopen

[@sad_man_no_talent]

@@ARandomUserOfThisWorld I just use a json file

[@everythingisfine9988]

💪👑

[@Alfakatt]

Us

[@cosmiclattemusic]

can't unsee NODE transitioning to DONE 😭

[@k00lmoh]

you mean DENO

[@orcagaming2143]

No he means done but it'll be oden before it because done😊

[@jackiedo7370]

NODE -> DENO -> ODEN -> DONE 🎉

[@erikjohnson9112]

Quicksort is not a stable sort. With a stable sort routine equal items will have the same relative order compared to the original. Quicksort does not have this feature. Most of the time you might not care, but that IS a difference worth noting.

[@dentjoener]

Thank you, and with sort getting faster on strings, it's probably trying to minimize comparisons, something TimSort does in Java and Python, because comparing is more expensive. Plus TimSort is stable.

[@eliasepg]

7:52 "you're good enough even when you're not at your best" love this statement, very deep

[@ErazerPT]

As pertains to the first example, repeat after me children : I shall NOT microbenchmark things where the function call overhead overshadows the work being done by an order of magnitude or more. Seriously, this is such a common thing it should be a meme for all intents and purposes. Now, show us a run where the work being done doesn't amount to "basically nothing at all", ie, something a tiny bit realistic...

[@noirsociety]

"Languages that try to disallow idiocy become themselves idiotic." -- Rob Pike

[@okie9025]

sounds a lot like rust to me

[@netssrmrz]

great quote. sounds like React to me.

[@randomuser66438]

​@@okie9025Here they come

[@shellderp]

The key point here is our programmers are Googlers, they’re not researchers. They’re typically, fairly young, fresh out of school, probably learned Java, maybe learned C or C++, probably learned Python. They’re not capable of understanding a brilliant language but we want to use them to build good software. So, the language that we give them has to be easy for them to understand and easy to adopt. It must be familiar, roughly C-like. Programmers working at Google are early in their careers and are most familiar with procedural languages, particularly from the C family. The need to get programmers productive quickly in a new language means that the language cannot be too radical. Actual Rob Pike quote

[@kasper_573]

The most important thing to measure is the performance of your application, not your modules or functions. Measure those once you’ve detected a performance issue with your app, and need to drill down as to why and fix the issue. A slow sum or sort is usually pointless to optimize if its impact on your app is negligible.

[@V3racious3]

This Deno commerical brought to you by Deno.

[@rawallon]

A Deno a day keeps the exception away

[@johnvomberg450]

The introduction was the most interesting part of this video.

[@k98killer]

Technically, there is a fifth way to loop: `for (let i=arr.length-1; i>=0; i--)` or `for (let i=0,l=arr.length; i

[@jakeave]

We've been able to squeeze out more by declaring i before and not using a lookup for the length. I know it sounds terrible, but it's ever so slightly faster. let i = 0; const len = arr.length for (; i < len; i++) Use at your own peril.

[@jerichaux9219]

I've done similar. As long as you maintain ownership over the array (to ensure the length isn't suddenly shorter than it was when you'd began), this is fine.

[@JasminUwU]

​@@jerichaux9219 That sounds like an absolutely horrible bug to discover

[@S7hadow]

I can see .length as having a slight overhead and so making a difference over a big number of loops. But the declaration of i doesn't seem logical to me as that part of the for loop is only run once. Guess I have to try Deno bench now

[@rumfordc]

@@S7hadow i believe the declaration is because scoping rules for loops are different from the rest of the function in javascript. the interpreter also needs to differentiate between which type of for-loop it is, which the semi-colon disambiguates immediately as opposed to reading the entire declaration before knowing which type of loop the declaration is for.

[@rumfordc]

also making that a while-loop should be faster than a for loop

[@zeikjt]

8:02 Yes, yes, noooooo! Using something like Deno bench doesn't tell you where bottlenecks in your program are! You need to profile your actual code in-situ. Then if you prove there's a bottleneck somewhere and it is affecting the performance of your program in a meaningful way then you can use bench to try and find faster alternatives, but then you need to test it again in-situ to make sure it actually performs better. You might have misunderstood the shape of the data, or the shape of the traffic to your code and find that your speed up didn't actually change much. You can't always test these things accurately synthetically, and you won't know it until you try it with the real thing :)

[@thepaintedsock]

Great video. The for loop can be sped up even more if you create the for(let i=0, len=arr.length; i < len; ++i)

[@r5LgxTbQ]

5:20 no fair, your benchmark doesnt account for the compute power to create the Set in the first place. You're not starting from the same place so it's not an accurate comparison

[@zeikjt]

Ideally you'd be using a Set from the get-go instead of an array, then you are starting from the same place. But if it's an all-at-once allocation instead of incremental then sure. This is why benchmarks are not ideal, test your real code to find actual bottlenecks and then you have the real situation.

[@sahilaggarwal2004]

The set example is not really accurate. Although I agree that it definitely provides performance benefits over Array.includes() in case of large data but while benchmarking we must also include the one time overhead taken to create the set as we are originally dealing with array data type.

[@aleksander5298]

that's why small array is faster than small set, but big set is faster than big array, you edgy boy

[@Slackow]

@@aleksander5298 big set is only faster if you actually keep the set up to date, and use it for multiple times, if you remake the set every single time then it's slower.

[@beyondfireship]

I disagree. The array is already in memory, so the Set should be too. The objective is to "find an element", not create the original data structure. One-time setup is insignificant on a task that runs millions of times. But just for fun, recreated the Set on each benchmark run and it still performed 20x faster.

[@aleksander5298]

@@Slackow why would you remake set lmao are you dumb? just use set instead of array, ez, you have skill issue or what?

[@sahilaggarwal2004]

@beyondfireship yeah that's what I said, set will be faster, no doubt in that. But the performance gain is not a million times faster if we consider the time to create the set too, and that's what I felt was inaccurate.

[@patric_forreal]

Using the SET trick to sort is much like using hash map ✅

[@lwinklly]

Anton mentioned 🎉

[@MelroyvandenBerg]

Yes he was. I'm recently creating quite some PRs for his tests 😅

[@Dominik-K]

Rob Pike mention ftw

[@RandomGeometryDashStuff]

06:49 unfair test! `[69,420].toSorted()` result is `[420,69]` but other sort functions output is `[69,420]`

[@mmanomad]

Love seeing more Deno videos!

[@pirixyt]

You forgot to loop with a while loop.

[@brandongregori995]

Probably the exact same as a for I loop

[@M0du5Pwn3n5]

It is worth saying: Knuth was talking about fiddling with bits in assembly. He was NOT talking about writing your programs in a basically performant way. He was CERTAINLY not saying "don't think about performance at all until later". Rob Pike's rules assume that you are writing your program in a sane way already, rather than in dog-slow nightmare spaghetti. There is a reason that Go is designed the way it is - it's not because all organizations of your program are equally valid and the structure doesn't matter until the end when you measure it. If you write your code in an inherently slow way, then once you measure it, it is too late. When you go to measure it, you will discover that there is no particularly expensive part you can optimize because the entire thing is sludge. Also, quicksort is not a fancy algorithm. It is known and extremely easy to copy. If you are not confident about your ability to google quicksort and write it correctly, you should find another career.

[@netssrmrz]

great video. would love to see a version for frontend.

[@tomasprochazka6198]

The initialization of Set takes some time though, should be included in the benchmark too

[@zeikjt]

Only if the Set is temporary, if you use a Set instead of an Array altogether then it's the same thing.

[@piff57paff]

Even then, there is more overhead during insertion. So you still need to look at it holistically.

[@zeikjt]

@@piff57paff i suppose it does depend on whether the data is always created in bulk or incremental. This is why you don't find bottlenecks via these kind of benchmarks, you time your real code so you know the situation

Deno is becoming awesome

[@vaisakh_km]

All thanks to bun.. Our cute little deno couldn't haddle the competition from Js's round buns XD

[@RustIsWinning]

​@@vaisakh_kmHahaha nice copium from the runtime with 500+ segfaults 😂

[@thatsalot3577]

​@@RustIsWinningyeah but you can't deny the fact that they're the reason why deno is atleast trying to do better because pre deno 2 there wasn't much reason to use it. And I find bun to be still pretty good for servers and web sockets

[@RustIsWinning]

@@thatsalot3577 Wrong. Yall just living under a rock and getting benchmarkbrainwashed by twitter influencer andys who are still stuck with the worse ecosystem lmao

[@vaisakh_km]

@@RustIsWinning there is no wrong or right... compatition is always improves the products.. period. I don't and never says bun is better than deno... deno will be always better at compatibility due to v8 engine

[@jackgame8841]

i could become performance engineer after this course

[@deatho0ne587]

forOf is my goto now a days for looping. One it is one of the faster and it is also easiest to think about in pseudocode.

[@QuentinBzt]

Bro is sold to the DENO cause, we wanna see Bun content as well 😛

[@danser_theplayer01]

I have one easy tip for performance. All array methods suck arse, and are hard to read, just write a for loop. This is the best answer every time all time. There is no question. If you do more than one thing then you'll chain methods without realising that you're looping more than once. Even if you don't chain, you still need to run a callback on methods. The for in/of loops are generators. Therefore the fastest is ALWAYS a regular for loop. I only write for loops because I don't know for sure that the array or object will be small enough, and also for loops are extremely versatile (doing what you usually do with 3 loop methods, in one loop), and readable.

[@oleg4966]

Eh, I'm quite fond of filter and sort methods. They're a PITA to translate to a pure for loop, and the resulting code is hard to read.

[@DomskiPlays]

Started a new job a few months ago and have fallen in love with maps and sets in combination with the data array. Fuck the users RAM, they want SPEED :D

[@brandongregori995]

You should look into sparse sets. They are pretty cool. It's like a faster map

[@WiseWeeabo]

let a = new Array(42); if (Object.seal) { a.fill(undefined); Object.seal(a); } Use fixed length arrays if you want to be fast.

[@codernerd7076]

Deno course!!!

[@gro967]

"scientifically faster" is the important part of the video title.

[@CottidaeSEA]

Premature optimization is no good, but don't write code with poor performance if you know it'll process a lot of data. It's not premature at that point.

[@amine7]

How else would you later make your service 5x faster and create a blog post and a youtube video bragging about it?

[@CottidaeSEA]

@amine7 Could do what a colleague of mine did. Do a big import, loop through the file and compare for every potential matching item in the database. That way I could improve the performance by 1000x.

[@nicsilver12]

Are you ok man? You sound a little down compared to your usual. Either way awesome video!

[@aleksander5298]

In the sumUsingForLoop you should make arr.length a separate variable to make it faster

[@whyneet]

In databases, the index lookup performance is not O(1), but O(log n) assuming the index uses a B-Tree

[@pixiedev]

Right, but he is not talking about database. it's for Set which uses hashing and is O(1) in almost every time.

[@Exilum]

Sets are almost always O(1), and the worst case isn't even that bad.

[@dave6012]

@@pixiedevhe compared the O(1) lookup of a Set to a database index, which as @whyneet pointed out, is not O(1).

[@MaulikParmar210]

Irony is people want performance from high level language like JS for which multiple runtime exists, each trying to impmement same stuff very differently from each other. If you really need it, than you won't be using JS or Go or even rust and rely C for close to metal performance. It also has own abstractions so it really drills down to a Software Engineers ability to understand machine at it's core level. Unfortunately alot of devs are not computer engineers or taught formally about computer architecture so squeezing out performance would be done by someone who excels in both relms and most of the world won't even need that kind of optimizations either. Thus compering benchmarks is pretty amature, at the end of the day solution and it's worthiness totally depends in usecase specific implementation. These type of comparison is inevitable because of lack of education on topics thst really matters after some point. And no if you're writing your app in JS for loading millions of records, that's not going to give you performance that a bare metal code will provide. Choose your tools wisely.

[@funkmedaddy]

In a perfect world you get to choose your tools, but we do not live in a perfect world and sometimes you're just given the tools and have to work with them. While it's worth pointing out that JS should not be your language of choice for performance oriented tasks, it doesn't mean you can't try and make the best of what you have

[@vighnesh153]

In the bubble sort implementation, I noticed that you were swapping variables using the array destructuring syntax: [a, b] = [b, a]. For small arrays, this is fine, but if the arrays are large, then creating a new array allocation just for swapping might also cause GC which will slow down the entire bubble sort impl. For benchmarking, it would be better to swap the variables the tradition way by creating a temp variable.

[@FirroLP]

If you can still change the video in your course: Not including the creation in the benchmark is a big flaw because creating a set is slower than an array. Obviously doesn't make such a difference, but it's a mistake and worth talking about

[@zeikjt]

I think y'all are thinking that you'd still have an Array, but why? Just use the Set the whole time, no need for the original Array.

[@jimbobu]

JavaScript developers when iterating over an array is slower than a single equality comparison: 🤯

[@82TheKnocKY]

These examples don't consider the fact that JavaScript is a JITed language. These microbenchmarks are never accurate to how little/much this function would actually get optimized if it was in a real application

[@sugaith]

these Rob Pike rules are perfect

[@JimmyCerra]

The Centauri write in Javascript. The Narn write in Python. The Shadows use C++. The Vorlons use Java.

[@npc-drew]

...and God write in Rust. 😎

[@theprantadutta]

Performance, you say, I have never heard of it.

[@edumorango]

One hash map to rule them all

[@zeikjt]

Lua got it figured out!

[@Roboprogs]

Thanks? I’ve been programming for 40 years, and these days I generally don’t worry about performance in the browser or Node, other than code and data size. The sort and search stuff pretty much all happens in the database. So I have to make all the execution time measurements against THAT, and avoid crippling it with stupid crap like ORM. So, yeah, same process, but not the place I run it. Batch C code on files in the 90s. Again, same process.

[@krowhenkvothe6010]

Like for the DENO course

[@npc-drew]

like because this account is a bot.

[@ciCCapROSTi]

Yeah, to be fair if you are speed conscious, you shouldn't use js. That doesn't mean you should ignore speed best practices of course. But doing big data in JS is just asking for trouble. That's what Python is for, with its C bindings.

[@RustIsWinning]

Deno is so winning!! B word could never 😂

[@kacaii3349]

More videos about Deno please!!

[@madbanana22]

Best js benchmarking strategy: 1. Are you using js outside the web frontend? 2. Don't

[@ktech4246]

All this time i have be using traditional for loops because I was too lazy to learn a cleaner way. Looks like my laziness has paid off!

[@muscifede]

code simple, test thoroughly, fix it

[@danser_theplayer01]

But if you're really looking to optimise a sorting algorithm, and have solid static typing, and don't want to learn a completely different language... Use a systems language like assemblyscript.

[@jordymaryns4945]

I hope there will be a lifetime purchase option in the future as well.

[@DoubleDYouTube]

When you're creating a new set of 10 000 elements, you're using a lot more memory in comparison to using "includes". It's still a much better solution, but I feel like it should be mentioned at least.

[@user-ii7xc1ry3x]

YAY new course!

[@RealRogerFK]

Unless you're doing a game, game server or something that's REALLY mission critical these silly little benchmarks are more of a "Okay, this little replacement takes me 10 mins to implement and saves me this much ram and lets me have up to 10K users instead of 1K" In reality, you don't even have 10 users, but at least you'll sleep well knowing Bun takes less RAM... b-because i-it does, r-right?

[@B1aQQ]

It's a misleading oversimplification to say the type of loop doesn't matter if the array is small. It might not matter if it runs infrequently. But if it's a part of a high traffic path, then you can have hundreds of small loop executions a second and that would mean the small differences can compound into an impactful performance hit.

[@trappedcat3615]

It matters if the array is large... or if the number runs on that small array is large

[@Kiyuja]

trad loop gave me life

[@pippinproductions]

java script users when they discover what a set is

[@stereocodes]

what's java script? Java users when they learn its actually Javascript and has nothing to do with Java.

[@unknownguywholovespizza]

​@@stereocodesit's so annoying when people say Java instead of JavaScript

[@fghdfghdfgghdstwesdfjtykjyfgk]

@@stereocodes but oracle owns javascript 🤔

[@robinmitchell6803]

5:16 -> Did you include the time to organise that array? If not, you can't compare the two.

[@BritishBagelGaming]

5:35 , thought it would be fair to include the initialisation of Set from the array within the benchmark, no?

[@itsmenewbie03]

Rust mentioned let's Goooooo 🦀🦀

[@MelroyvandenBerg]

Gooo also mentioned

[@MelroyvandenBerg]

Gooo also mentioned 😅

[@RustIsWinning]

Winning! Zig could never lmao 🦀🦀

[@floppa9415]

"Premature optimization is the root of all evil" is one of the dumbest quotes, especially if you think about things on a larger scale. If your architecture is stupid and leads to brutal overhead, for example by needlessly splitting up things into microservices that communicate over rest, you can't "optimize" yourself out of that easily. At that point you have to basically start over.

[@morchellemusic2829]

I think you got the quote wrong dude 😂

[@musicstar8885]

Best video till date

[@MelroyvandenBerg]

Instant tinnitus due to your sound effects 😢

[@JJJMMM1]

5:40 the analogy between database indexes and O(1) Set lookups doesn't make sense to me. Most database indexes are stored as B-trees or B+trees, and the lookup complexity there is O(log n). So either the time complexity of a Set lookup is also O(log n), or the Set is actually stored as a hashmap - which is what I would've guessed - giving you an average case of ~ O(1).

[@IngwiePhoenix]

So, how many "nodejs-bench" packages do exist by now?

[@sugarsama7716]

It's kinda misleading... I run a bench with the same quicksort implementation, and it was about 97% slower than Array.prototype.sort,

[@ucmRich]

*** How can we put JavaScript (or the whole deno) in a cpp program for use as a scripting language for programming game logic in a 3D game engine? DXStudio used JavaScript as it's scripting language and I want to put that into another game engine or just make my own game engine with JS. Can Deno be used for this?

[@darkenlightmage]

If you include and link the node or deno (or just the V8) runtime with the project, you can directly invoke the interpreter inside whatever application you want. It is then a matter of passing the right values to the interpreter environment so that you can modify external values using JS.

[@AndreSpecht]

Amazing video. Could you share the code? Would love to use it with my students

[@Filaxsan]

GOLD video!

[@alekseykarpenko2681]

Would these results be different in Node?

[@cathalogrady2331]

I feel like you have to apply pikes principles a bit different considering JS doesn't even have an optimizer.

[@AvanaVana]

Why didn’t you include the array to set conversion in the benchmark for set?

[@marcmcintosh6715]

can you add to the suite? ``` function sum(arr: number[], count = 0) { if (arr.length === 0) return count; const [head, ...tail] = arr; return sum(tail, count + head) } ```

[@mateja176]

I wish JavaScript had zero cost abstractions.

[@floppa9415]

At this point you don't have JS

[@thatsalot3577]

Dude it was supposed to be a frontend language, which runs in browser and was used to make buttons go click click, at this point you just like the js syntax.

[@monawoka97]

Traditional for loop is fastest. C chads knew it all along.

[@narrei666]

does set also work this well for array of objects?

[@ence7846]

no

[@turun_ambartanen]

at 5:40-5:50 you say that a JS set is like a DB index. Is it really? I would have expected the set to work on hashes, but the index to work on a balanced binary tree.

[@ence7846]

This is an implementation detail but Set are just binary tree in js, like Map

[@jontancool9181]

This was uploaded at a perfect time as i was planning to work with benchmarking of a framework for my exam work

[@Waterfly-v7q]

Nice guide how to look at JS (meaning the most popular runtime V8) perf like a amateur xd

[@brogotbonkers]

that's an ad? I've tried to create a blog with Deno but it really sucked. not even close to what Ryan promised on demos lol

[@RandomGeometryDashStuff]

06:22 does `[result[j], result[j+1]] = [result[j+1], result[j]];` create and iterate array?

[@codyrap95]

It creates a temporary array in memory and then destructures it as it's easier than creating a third variable to store the temporary value of result[j]

[@LuanDavi]

amazing content!

[@anb4351]

Damn foreach loop is bad. I have pretty large foreach loops throughout my codebase

[@tomasprochazka6198]

Why it isn't optimized by a compiler ... oooh

[@fermin7c1]

You keep calling functions passed to a method "callbacks" when they are just functions, nothing is calling back to them, they are just executed

[@1apostoli]

strings sort by radix

[@robchr]

What is the zeroith rule?

[@anotherone2398]

use C.

[@samuelebernardi1162]

Wouldn't the time to copy the array items to a set be longer than the actual research?

[@mrdmajor]

It's hilarious watching web developers rant about performance but then also be hypebeasts for bloated frameworks, to build "apps". 🤣

[@jeevandza3464]

can you tell about WinterJS

[@WiseWeeabo]

K-nooth