Eddie

Maker, designer, developer • he/him • Engineer @Arm

[Eddie @onfe1]

I've left twitter, find me on https://t.co/EPoZG82PzP

[theall3ycat @TheAll3ycat]

circles were never the real danger

[Daniel Lemire @lemire]

The fast JavaScript runtime Bun is much faster than Node.js 22 at decoding Base64 inputs. By much faster, I mean *several times* faster. But they both rely on the same underlying library (simdutf) for the actual decoding.

So what gives?

The problem is that Node.js needs to interact with v8, the underlying JavaScript engine (from Google)... and doing so is not trivial.

Before we can start decoding the string, we need to grab the string... so, in this instance, we call String::Value...

In turns, this allocates an array inside Node.js and asks v8 to copy the content to it...
In an ideal world, we would avoid the trouble entirely and just ask v8 to give us direct access to how it stores the string... and we try to do that if we can... but let me come back to it...

How bad can this be, right? Just a copy.

Well. Let us do some profiling...

So you see, the base64 decoding itself is about about 1/5 of the running time, but the copy takes half of it.

What is up with this CopyChars function? Well, it is mostly just a wrapper around the standard high level C++ function std::copy_n as far as I can tell. (see v8/src/utils/memcopy.h)

But we are copying for an 8-bit input to a 16-bit output... why is that? Base64 is pure ASCII... and v8 can store ASCII using 8-bit per character.

We get there before both IsExternalOneByte() and IsOneByte() are false (see node/src/node_buffer.cc)... We have fast paths for these cases. If IsExternalOneByte() is true, we just get the bytes and everything is great. Unfortunately, it does not always work.

So we have a v8 string that is really pure ASCII, but, seemingly, we can't tell that it is the case from Node.js, and so we have to convert it to UTF-16 needlessly, using a function that is maybe not very well optimized... and then we do the base64 decoding of an ASCII string from the UTF-16 input. It is not great.

To be fair, this is just one string, created as 'Buffer.alloc(size, "latin1").toString("base64")', basically the base64 encoded version of the string "latin1latin1latin1...". In actual applications, we might have better luck.

Yet. Yet. I am telling this complicated story for a reason.

The story illustrates why our software is slower than it should be. We have layers of abstractions to fight against. Sometimes you win, sometimes you lose.

These layers are there for a reason, but they are not free.

To make matters worse... these abstraction layers often thicken over time... and the friction goes up.

To be clear, I do not claim that the Node.js code is optimal. In fact, I know it can be better. But it is not trivial to make it go fast.

I sometimes hear people say... "well, it is C++ and C++ is hard". No. The C++ part is easy relatively speaking. The difficulty is at a higher level. It is not a matter of syntax. It is a matter of architecture.

[Tantacrul (@tantacrul.bsky.social) @Tantacrul]

1. I'm legit shocked by the design of @Meta's new notification informing us they want to use the content we post to train their AI models. It's intentionally designed to be highly awkward in order to minimise the number of users who will object to it. Let me break it down.

[Eddie @onfe1]

it's the last day of the pre-order
if you want a real popcat, now's your chance

🔗 https://t.co/jSZgyXTDlX

[Eddie @onfe1]

the boy... he is here

[Eddie @onfe1]

I added this feature!! 🤗
popopop in plushie mode 👏👏

[Eddie @onfe1]

y'all best be glad my mspaint skills never made the cut for @popcatclick

[Eddie @onfe1]

@geromegamzing @youtooz I think it looks quite good IRL, but thanks for the feedback - what would you change?

[Eddie @onfe1]

We've been working with @youtooz to bring out this https://t.co/NjJK80Fb5E plushie

It'll be available very soon, for a limited time⏳

[caesararum, BS, DOGS @caesararum]

"The customer has nuclear weapons"

https://t.co/XMnEZhlzWs

[trash jones @jzux]

surely this is the three day weekend that will replenish my will to live

[cje @caseyjohnellis]

he’s making a list,
he’s checking it twice,
he’s gonna find out who's naughty or nice,
santa claus is in contravention of article 4 of the General Data Protection Regulation (EU) 2016/679.

[terminally onλine εngineer @tekbog]

you know those services I refactored without filling a jira ticket?

[popcat.click @PopCatClick]

✨🆕 https://t.co/rpW6xTVab1 🆕✨
🛍️🙀 POP! POP! POP! POP! 🙀🛍️

[Thing Bad @Merman_Melville]

kind of a bummer to have been born at the very end of the Fuck Around century just to live the rest of my life in the Find Out century

[Sebastiaan de With @sdw]

This is missing the coolest one: the actual first Photoshop icon which is a literal… photo shop