Replacing Protobuf with Rust to go 5 times faster

114 pointsposted 7 hours ago
by whiteros_e

74 Comments

GuB-42

2 hours ago

What I find particularly ironic is that the title make it feel like Rust gives a 5x performance improvement when it actually slows thing down.

The problem they have software written in Rust, and they need to use the libpg_query library, that is written in C. Because they can't use the C library directly, they had to use a Rust-to-C binding library, that uses Protobuf for portability reasons. Problem is that it is slow.

So what they did is that they wrote their own non-portable but much more optimized Rust-to-C bindings, with the help of a LLM.

But had they written their software in C, they wouldn't have needed to do any conversion at all. It means they could have titled the article "How we lowered the performance penalty of using Rust".

I don't know much about Rust or libpg_query, but they probably could have gone even faster by getting rid of the conversion entirely. It would most likely have involved major adaptations and some unsafe Rust though. Writing a converter has many advantages: portability, convenience, security, etc... but it has a cost, and ultimately, I think it is a big reason why computers are so fast and apps are so slow. Our machines keep copying, converting, serializing and deserializing things.

Note: I have nothing against what they did, quite the opposite, I always appreciate those who care about performance, and what they did is reasonable and effective, good job!

phkahler

2 hours ago

>> But had they written their software in C, they wouldn't have needed to do any conversion at all. It means they could have titled the article "How we lowered the performance penalty of using Rust".

That's not really fair. The library was doing serialization/deserialization which was poor design choice from a performance perspective. They just made a more sane API that doesn't do all that extra work. It might best be titles "replacing protobuf with a normal API to go 5 times faster."

BTW what makes you think writing their end in C would yield even higher performance?

the__alchemist

2 hours ago

I wonder why they didn't immediately FFI it: C is the easiest lang to write rust binding for. It can get tedious if using many parts of a large API, but otherwise is straightforward.

I write most of my applications and libraries in Rust, and lament that most of the libraries I wish I would FFI are in C++ or Python, which are more difficult.

Protobuf sounds like the wrong tool. It has applications for wire serialization and similar, but is still kind of a mess there. I would not apply it to something that stays in memory.

vlovich123

25 minutes ago

It’s trivial to expose the raw C bindings (eg a -sys crate) because you just run bindgen on the header. The difficult part can be creating safe, high-performance abstractions.

kleton

an hour ago

>Protobuf sounds like the wrong too This sort of use for proto is quite common at google

kccqzy

an hour ago

No it’s not common for two pieces of code within a single process to communicate by serializing the protobuf into the wire format and deserializing it.

It’s however somewhat common to pass in-memory protobuf objects between code, because the author didn’t want to define a custom struct but preferred to use an existing protobuf definition.

logicchains

2 hours ago

> they had to use a Rust-to-C binding library, that uses Protobuf for portability reasons.

That sounds like a performance nightmare, putting Protobuf of all things between the language and Postgres, I'm surprised such a library ever got popular.

formerly_proven

42 minutes ago

> I'm surprised such a library ever got popular.

Because it is not popular.

pg_query (TFA) has ~1 million downloads, the postgres crate has 11 million downloads and the related tokio-postgres crate has over 33 million downloads. The two postgres crates currently see around 50x as much traffic as the (special-purpose) crate from the article.

cranx

4 hours ago

I find the title a bit misleading. I think it should be titled It’s Faster to Copy Memory Directly than Send a Protobuf. Which then seems rather obvious that removing a serialization and deserialization step reduces runtime.

MrDarcy

3 hours ago

TIL serializing a protobuf is only 5 times slower than copying memory, which is way faster than I thought it’d be. Impressive given all the other nice things protobuf offers to development teams.

dietr1ch

2 hours ago

I guess that number is as good or as bad as you want with the right nesting.

Protobuf is likely really close to optimally fast for what it is designed to be, and the flaws and performance losses left are most likely all in the design space, which is why alternatives are a dime a dozen.

cmrdporcupine

an hour ago

I wouldn't hold onto that number as any kind of fixed usable constant since the reality will depend entirely on things like cache locality and concurrency, and the memory bandwidth of the machine you're running on.

Go around doing this kind of pointless thing because "it's only 5x slower" is a bad assumption to make.

nicman23

3 hours ago

that actually crazy fast

bluGill

2 hours ago

Protobuf does something important that copying memory cannot do: a protocol that can be changed separately on either end and things can still work. You have to build for "my client doesn't send some new data" (make a good default), or "I got extra data I don't understand" (ignore it). However the ability to upgrade part of the system is critical when the system is large and complex since you can't fix everything to understand your new feature without making the new feature take ages to roll out.

Protobuf also handles a bunch of languages for you. The other team wants to write in a "stupid language" - you don't have to have a political fight to prove your preferred is best for everything. You just let that team do what they want and they can learn the hard way it was a bad language. Either it isn't really that bad and so the fight was pointless, or it was but management can find other metrics to prove it and it becomes their problem to decide if it is bad enough to be worth fixing.

vlovich123

24 minutes ago

But something more modern that doesn’t have the encoding/decoding penalty of Protobuf would be better (eg cap’n’proto but there’s a bunch now in this space).

miroljub

4 hours ago

Yep.

Just doing memcpy or mmap would be even faster. But the same Rust advocates bragging about Rust speed frown upon such unsecure practices in C/C++.

infogulch

an hour ago

Why don't we use standardized zero-copy data formats for this kind of thing? A standardized layout like Arrow means that the data is not tied to the layout/padding of a particular language, potential security problems like bounds checks are automatically handled by the tooling, and it works well over multiple communication channels.

lenkite

2 hours ago

How we used Claude and bindgen to make Rust catch up with C's 5x performance.

nottorp

6 hours ago

Are they sure it's because Rust? Perhaps if they rewrite Protobuf in Rust it will be as slow as the current implementation.

They changed the persistence system completely. Looks like from a generic solution to something specific to what they're carrying across the wire.

They could have done it in Lua and it would have been 3x faster.

consp

6 hours ago

If they made the headline something on the line of "replacing protobuf with a native, optimized implementation" would not get the same attention as putting rust in the title to attract the everything-in-rust-is-better crowd.

desiderantes

5 hours ago

That never happens. Instead, it always attracts the opposite group, the Rust complainers, where they go and complain about how "the everything-in-rust-is-better crowd created yet another fake headline to pretend that Rust is the panacea". Which results in a lot of engagement. Old ragebait trick.

hu3

3 hours ago

At the very least it gets more upvotes.

timeon

2 hours ago

Well it is keyword for RSS feeds.

embedding-shape

6 hours ago

It's devbait, not many of us can resist bikeshedding about the title which obviously doesn't accurately reflect the article contents. And the article contents are self-aware enough to admit this to itself too, yet the title remains.

alias_neo

6 hours ago

I was equally confused by the headline.

I wonder if it's just poorly worded and they meant to say something like "Replacing Protobuf with some native calls [in Rust]".

misja111

6 hours ago

Correct, this has very little to do with Rust. But it wouldn't have made the front page without it.

win311fwg

6 hours ago

The title would suggest that it was already written in Rust; that it was the rewrite in Go that brought five times faster.

locknitpicker

6 hours ago

Yes you are absolutely right. The article even outright admits that Rust had nothing to do with it. From the article:

> Protobuf is fast, but not using Protobuf is faster.

The blog post reads like an unserious attempt to repeat a Rust meme.

rozenmd

5 hours ago

"5 times faster" reminds me of Cap'n Proto's claim: in benchmarks, Cap’n Proto is INFINITY TIMES faster than Protocol Buffers: https://capnproto.org/

7777332215

5 hours ago

In my experience capn proto is much less ergonomic.

IshKebab

2 hours ago

I agree. It might be faster if you don't actually deserialise the data into native structs but then your codebase will be filled with fairly horrific CapnProto C++ code.

gf000

5 hours ago

I mean, cap'n'proto is written by the same person who created protobuf, so they are legit (and that somewhat jokish claim is simply that it requires no parsing).

Sesse__

4 hours ago

> I mean, cap'n'proto is written by the same person who created protobuf

Notably, Protobuf 2, a rewrite of Protobuf 1. Protobuf 1 was created by Sanjay Ghemawat, I believe.

7e

3 hours ago

Google loves to reinvent shit because they didn't understand it. And to get promo. In this case, ASN.1. And protobufs are so inefficient that they drive up latency and datacenter costs, so they were a step backwards. Good job, Sanjay.

notyourwork

25 minutes ago

Really dismissive and ignorant take from a bystander. Back it up with your delivery that does better instead of shouting with a pitchfork for no reason.

suriya-ganesh

38 minutes ago

This is an unfair comparison.

using a transport serialization and deserialization protocol for IPC. It is obvious why there was an overhead because it was architectural decision to manage the communication.

I guess the old adage of if something goes 20% faster something was improved if it is 10x faster, it was just built wrong is true here.

yodacola

6 hours ago

FlatBuffers are already faster than that. But that's not why we choose Protobuf. It's because a megacorp maintains it.

nindalf

6 hours ago

You're saying we choose Protobufs [1] because Google maintains it but not FlatBuffers [2]?

[1] - https://github.com/protocolbuffers/protobuf: Google's data interchange format

[2] - https://github.com/google/flatbuffers: Also maintained by Google

rafaelmn

5 hours ago

I get the OP is off base with his remark - but at the same time maintained by Google means shit in practice.

AFAIK they have a bunch of production infra on protobuff/gRPC - not so sure about flatbufferrs which came out of the game dev side - that's the difference maker to me - which project is actually rooted in.

dewey

5 hours ago

> but at the same time maintained by Google means shit in practice.

If you worked on Go projects that import Google protobuf / grpc / Kubernetes client libraries you are often reminded of that fact.

whoevercares

3 hours ago

Flatbuffers are fine - I think it is used in many places that needs zero-copy. Also outside google, it powers the Arrow format which is the foundation of modern analytics

secondcoming

5 hours ago

Yet they've yet to release their internal optimisation that allows zero-copying string-type fields.

lowdownbutter

5 hours ago

Don't read clickbaity headlines and scan hacker news five times faster.

chuckadams

2 hours ago

Become a 5X Hacker News reader with this One Weird Trick.

t-writescode

5 hours ago

Just for fun, how often do regular-sized companies that deal in regular-sized traffic need Protobuf to accomplish their goals in the first place, compared to JSON or even XML with basic string marshalling?

izacus

3 hours ago

I dunno, are you sure you can manually write correct de/serializaiton for JSON and XML so strings, floats and integer formats correctly get parsed between JavaScript, Java, Python, Go, Rust, C++ and any other languages?

Do you want to maintain that and debug that? Do you want to do all of that without help of a compiler enforcing the schema and failing compiles/CI when someone accidentally changes the schema?

Because you get all of that with protobuf if you use them appropriately.

You can of course build all of this yourself... and maybe it'll even be as efficient, performant and supported. Maybe.

nicman23

3 hours ago

i mean you can always go mono or duo language and then it is really not that of an issue

eklavya

2 hours ago

That would make sense if protobuf was complex, bloated, slow. But it's not, so the question should be why not use it, unless you are doing browser stuff.

9rx

an hour ago

If you are going to use it elsewhere, why not use it for browser stuff too?

tcfhgj

5 hours ago

Well, protobuf allows to generate easy to use code for parsing defined data and service stubs for many languages and is one of the faster and less bandwidth wasting options

vouwfietsman

4 hours ago

Besides the other comments already here about code gen & contracts, a bigger one for me to step away from json/xml is binary serialization.

It sounds weird, and its totally dependent on your use case, but binary serialization can make a giant difference.

For me, I work with 3D data which is primarily (but not only) tightly packed arrays of floats & ints. I have a bunch of options available:

1. JSON/XML, readable, easy to work with, relatively bulky (but not as bad as people think if you compress) but no random access, and slow floating point parsing, great extensibility.

2. JSON/XML + base64, OK to work with, quite bulky, no random access, faster parsing, but no structure, extensible.

3. Manual binary serialization: hard to work with, OK size (esp compressed), random access if you put in the effort, optimal parsing, not extensible unless you put in a lot of effort.

4. Flatbuffers/protobuf/capn-proto/etc: easy to work with, great size (esp compressed), random access, close-to-optimal parsing, extensible.

Basically if you care about performance, you would really like to just have control of the binary layout of your data, but you generally don't want to design extensibility and random access yourself, so you end up sacrificing explicit layout (and so some performance) by choosing a convenient lib.

We are a very regularly sized company, but our 3D data spans hundreds of terabytes.

(also, no, there is no general purpose 3D format available to do this work, gltf and friends are great but have a small range of usecases)

physicsguy

3 hours ago

This was the norm many years ago, I worked on a simulation software which existed long before Protobuf was even an apple in it's authors eyes. The whole thing was on a server architecture with a Java (later ported to Qt) GUI and a C++ core. The solver periodically sent data in a custom binary format over TCP for vector fields and things.

bluGill

5 hours ago

In most languages protobuf is eaiser because it generates the boilerplate. And protobuf is cross language so even if you are working in javascript where json is native protobuf is still faster because the other side can be whatever and you are not spending their time parsing.

tuetuopay

4 hours ago

Type safety. The contract is the law instead of a suggestion like JSON.

Having a way to describe your whole API and generate bindings is a godsend. Yes, it can be done with JSON and OpenApi, yet it’s not mandatory.

9rx

18 minutes ago

> Yes, it can be done with JSON and OpenApi, yet it’s not mandatory.

It is not mandatory for Protobuf either. You can construct a protobuf message with an implied structure just as you can with JSON. It does not violate the spec.

Protobuf ultimately gets the nod because it has better tooling (which isn't to be taken as praise towards Protobuf's tooling, but OpenAPI is worse).

Chiron1991

4 hours ago

It's not just about traffic. IoT devices (or any other low-powered devices for that matter) also like protobuf because of its comparatively high efficiency.

pjmlp

3 hours ago

I never used it, coding since 1986.

jonathanstrange

4 hours ago

Protobuf is fantastic because it separates the definition from the language. When you make changes, you recompile your definitions to native code and you can be sure it will stay compatible with other languages and implementations.

speed_spread

3 hours ago

You mean like WSDL, OpenAPI and every other schema definition format?

Well I agree. Contract-first is great. You provide your clients with the specs and let them generate their own bindings. And as a client they're great too because I can also easily generate a mock server implementation that I can use in tests.

linuxftw

3 hours ago

Many people are exclaiming that the title is baity, but I disagree. It seems like a perfectly fine title in the context of this blog, which is about a specific product. It's unlikely they wrote the blog with a HN submission in mind. They're not a news publication, either.

unnouinceput

2 hours ago

Quote: "We forked pg_query.rs and replaced Protobuf with direct C-to-Rust (and back to C) bindings, ...."

So it's C actually, not Rust. But Hey! we used Rust somewhere, so let's post it on HN and farm internet points.

spwa4

4 hours ago

You should be terrified of the instability you're introducing to achieve this. Memory sharing between processes is very difficult to keep stable, it is half the reason kernels exist.

sylware

4 hours ago

I don't understand, I used protobuf for map data, but it is a hardcore simple format, this is the whole purpose of it.

I wrote assembly, memory mapping oriented protobuf software... in assembly, then what? I am allowed to say I am going 1000 times faster than rust now???

IshKebab

6 hours ago

I vaguely recall that there's a Rust macro to automatically convert recursive functions to iterative.

But I would just increase the stack size limit if it ever becomes a problem. As far as I know the only reason it is so small is because of address space exhaustion which only affects 32-bit systems.

jeroenhd

5 hours ago

Explicit tail call optimization is in the works but I don't think it's available in stable jut yet.

The `become` keyword has already been reserved and work continues to happen (https://github.com/rust-lang/rust/issues/112788). If you enable #![feature(explicit_tail_calls)] you can already use the feature in the nightly compiler: https://play.rust-lang.org/?version=nightly&mode=debug&editi...

(Note that enabling release mode on that link will have the compiler pre-calculate the result so you need to put it to debug mode if you want to see the assembly this generates)

embedding-shape

6 hours ago

> I vaguely recall that there's a Rust macro to automatically convert recursive functions to iterative.

Isn't that just TCO or similar? Usually a part of the compiler/core of the language itself, AFAIK.

koverstreet

5 hours ago

I haven't been following become/TCO in Rust - but what I've usually seen is TCO getting flipped off because it interferes with backtraces and debugging.

So I think there's value in providing it as an explicit opt-in; that way when you're reading the code, you know to account for it when you're looking at backtraces.

Additionally, if you're relying on TCO it might be a major bug if the compiler isn't able to apply it - and optimizations that aren't applied are normally invisible. This might mean you could get an error if you're expecting TCO and you or the compiler screwed something up.

tialaramex

4 hours ago

In a language like Rust where local variables are explicitly destroyed when scope ends a naive TCO is very annoying and `become` also helps fix that.

Suppose I have a recursive function f(n: u8) where f(0) is 0 and otherwise f(n) is n * bar(n) + f(n-1)

I might well write that with a local temporary to calculate bar(n) and then we do the sum, but this would inhibit TCO because that temporary should exist after we did the recursive calculation, even though it doesn't matter in practice.

A compiler could try to cleverly figure out whether it matters and destroy that local temporary earlier then apply TCO, but now your TCO is fragile because a seemingly minor code change might fool that "clever" logic, by ensuring it isn't correct to make this change and breaking your optimisation.

The `become` keyword is a claim by the programmer that we can drop all these locals and do TCO. So because the programmer claimed this should work they're giving the compiler permission to attempt the early drop and if it doesn't work and can't be TCO then complain that the program is wrong.

steeve

5 hours ago

tldr: they replaced using protobuf as the type system across language boundaries for FFI with true FFI

ahartmetz

3 hours ago

Title is as nonsensical as "We replaced Windows with ARM CPUs"

Xunjin

5 hours ago

I loved, every clickbait title should come with a tldr just like this one.

xxs

4 hours ago

if you see an order of magnitude difference and a language involved in the title, it's something I refuse to read (unless it's an obvious choice - interpret vs compilied/jit one)