Proxygen, Facebook's C++ HTTP Framework

https://code.facebook.com/posts/1503205539947302/introducing-proxygen-facebook-s-c-http-framework/

by mikeevans • 12 years ago

324 89 12 years ago

code.facebook.com

dcsommer14• 12 years ago

Hey there, I work on Proxygen at Facebook. I'm happy to answer any questions you have about the project.

brian_herman• 12 years ago

Are there any plans for spdy and http2?

spicyj• 12 years ago

From the first paragraph:

In addition to HTTP/1.1, Proxygen (rhymes with "oxygen") supports SPDY/3 and SPDY/3.1. We are also iterating and developing support for HTTP/2.

seasonedschemer2• 12 years ago

We already do support SPDY/3 and SPDY/3.1, and we're working on HTTP/2 currently.

invisible2• 12 years ago

Hey! So Proxygen was originally a reverse-proxy load balancer. Is that still how Facebook utilizes it now? If not, what is its current role? Are there any plans for integrating this with Hiphop/PHP in any way?

dcsommer14• 12 years ago

Yup, we still use Proxygen (the library) in our reverse proxy. Maybe some day we'll be able to open source the reverse proxy too, but it's pretty deeply integrated with internal FB code right now so that's tricky.

We already use the Proxygen HTTP code for the webserver part of HHVM internally. We hope to release that webserver part too (in the HHVM project).

drefined• 12 years ago

The blog post mentions that HHVM uses parts of Proxygen.

mikebo• 12 years ago

How tested is the websocket support? Does facebook use this for TLS termination?

dcsommer14• 12 years ago

Websocket support isn't out yet unfortunately. It's something we hope to get to soon.

Our reverse proxy uses proxygen and does TLS termination too, yes.

mattgodbolt• 12 years ago

If you need a really simple embeddable C++ webserver that supports websockets (and as the primary developer) can I suggest SeaSocks: https://github.com/mattgodbolt/seasocks

lost_name• 12 years ago

This question is a bit naive, but outside of Facebook, can you think of what kind of application this is well suited for?

swartkrans• 12 years ago

Any kind of internal service that listens and accepts an API. Like you could put a bunch of monitoring agents on all your machines and those agents get information about your machines and report back to the service that makes use of Proxygen. Your service would use Proxygen instead of hiding behind an nginx or apache server and running via some kind of fcgi setup. The agents themselves could be using the Proxygen client to talk to the service using Proxygen server pieces.

dcsommer14• 12 years ago

Well besides the fun of hacking around and building little HTTP servers, I could see this being useful if you want to save money by running fewer instances of your HTTP service. For instance, if you have a widely deployed python webservice that isn't scaling well, you could rewrite it in C++ with very little boilerplate using proxygen's httpserver.

It's early stages for the proxygen open source project. Maybe further down the road we'll provide off-the-shelf binaries, but we think the library is already interesting enough to warrant a release.

plainOldText• 12 years ago

I'm curious to know why there is a file named PATENTS in the repo (alongside the LICENSE file). What kind of legal protections would this "additional grant" give you?

dcsommer14• 12 years ago

This is similar to the Apache License, which allows developers to use the project with the confidence that we grant a license to any patents that may affect the project. This is a grant we use for all of our projects and is not anything specific to Proxygen.

leeber• 12 years ago

I currently use nginx for all my projects, which for me mostly consist of (1) serving static content and (2) proxying to gunicorn. My setups are usually not overly complicated, basic redirects for stuff like www/non-www or ssl/non-ssl, installing ssl certs can be a pain sometimes, and for the most part I use a lot of default settings and have never needed to go in-depth with tweaking settings.

Does somebody like me have a reason to check out Proxygen?

dcsommer14• 12 years ago

Maybe not today. We haven't open sourced a configurable proxy yet, so you wouldn't be able to do your redirects and some of these other features without writing C++ code.

If you're interested in how HTTP frameworks are designed and implemented, I'd definitely suggest checking it out though. This project is initially going to be more interesting to people integrating with HTTP quite directly.

egonschiele2• 12 years ago

I would love to see a comparison between Proxygen and another server (ideally nginx or golang server). The numbers are impressive, but the client is on the same box, it is a big box, and it is a simple and short response. So I'm not sure if I should be wowed or not. From reading the post, Proxygen was written as a server that would be well-integrated into Facebook tools. I don't really use Facebook tools, so I'm not sure if Proxygen would be right for me?

dcsommer14• 12 years ago

I think https://news.ycombinator.com/item?id=8563766 is a good answer to use cases.

thrownaway2424• 12 years ago

Could you comment on the verisimilitude of the benchmark parameters? I would expect in Facebook's production environment the number of active sockets would be hundreds or thousands of times greater than 400.

dcsommer14• 12 years ago

You're right we see many more connections in production. We didn't have enough time to run exhaustive benchmarks for all the different possible combinations of active sockets, requests per connection, etc. As you might suspect, 400 was a sweet spot for our performance numbers at 1 core. Overall RPS didn't dip too much when increasing the number of connections. The table we included is just to give a rough idea of perf.

sitkack• 12 years ago

What are the security implications of running native code on a public facing service? How many RCEs has Proxygen had? Has it been audited for security? What is the testing procedure?

dcsommer14• 12 years ago

In general, native code is not the same as unsafe code (that's why I'm personally excited about Rust. Native + safe = awesome). In C++'s case though it is true that a memory error could be used to exploit the process. Careful use of safe memory abstractions are our main safeguard against this. I can't comment on RCEs, but Proxygen has been externally and internally audited for security. We have many unit tests in the project, and we also internally have more comprehensive integration tests and a fuzzer.

djb_hackernews• 12 years ago

Question for you and the general C++ community. I am a Java developer mostly but it looks like I'll be transitioning to a few C++ projects in the near future. Any good resources you can recommend for learning modern C++? Particularly anything you've used to get developers on your team similarly up to speed.

I've cruised through the Proxygen code base and there are definitely some head scratchers.

krate• 12 years ago

This SO thread has a good overview of the books out there:

http://stackoverflow.com/questions/388242/the-definitive-c-b...

I'd recommend "C++ Primer" first, "Effective C++" second, and "The C++ Programming Language" as a reference. Other must haves are "Modern C++ Design", the other Scott Meyers books, and the Herb Sutter books.

pjmlp3• 12 years ago

You surely should pick Bjarne's latest book, "Tour of C++".

It is show how to make proper use of C++11 without any bad C influences.

syncopate• 12 years ago

Hey, I am a bit late, but I wonder how you generally handle unicode in C++, since the language itself does not have much support for it. That's what always makes me weary of writing any kind of server in C++.

optymizer• 12 years ago

By using icu::UnicodeString.

Docs: http://icu-project.org/apiref/icu4c/classicu_1_1UnicodeStrin...

Site: http://site.icu-project.org/

matt_d• 12 years ago

Hi! Looks interesting!

I have a question -- in particular, the blog post mentions that the framework "includes both server and client code", any my question is about the second part :-)

I'm wondering, how does it compare to the other C++ HTTP client solutions: Is it closer to higher-level libraries like cpp-netlib, Casablanca, or POCO -- or more on a lower-level / comparable to Asio (or Boost.Asio)?

In your view, what are the main relative advantages/disadvantages (namely in the scenario mentioned in the blog post, i.e., integration into existing applications)?

cthulhuology• 12 years ago

what are the units on the table? the top looks like number of workers, but large numbers are unitless.

dcsommer14• 12 years ago

It's requests per second (averaged over a 60 second test run).

thomasreggi• 12 years ago

"You will need at least 2 GiB of memory to compile proxygen and its dependencies." What?

btian• 12 years ago

That is not unreasonable for modern software. You don't need 2GB of RAM to use it.

port8080• 12 years ago

fbthrift needs 2GiB of memory to compile (https://github.com/facebook/fbthrift) and proxygen has a dependency on fbthrift.

userbinator• 12 years ago

That then begs the question of what in fbthrift needs so much memory... is it mainly due to heavy use of C++ features like template metaprogramming?

chaotic-good• 12 years ago

Offtopic: I have a problem using fbthrift and cpp2 server together. I'm find that there is two IDL to C++ compilers that I need to use - one old thrift compiler written in C++ and the new one written in python. Code generated by both this compilers is used in tests! Is there any tutorial or article with step by step instructions?

maccard• 12 years ago

i wouldnt like to try compiling my work projects on anything less than 16GB ram, never mind 2GB

Igglyboo2• 12 years ago

Completely reasonable for modern software of this size/complexity.

pcunite• 12 years ago

Excellent, I've been toying around with my own and looking at LibUV. I think the time is right for something like this. I want to maintain state on everything that connects to me.

beliu• 12 years ago

dcsommer (author of proxygen) gave a great talk about this at the last Sourcegraph open-source meetup. Here's the video: https://www.youtube.com/watch?v=-yxQIRl6Qic

dcsommer14• 12 years ago

I'm flattered, but I'm just an author. Proxygen is the work of about a dozen people over 4 years at Facebook.

b3tta2• 12 years ago

I really like your idea of the 4-part abstraction. Still… Your library really is not "that" easy to use.

I'm currently working on my own library using libuv, http-parser, nghttp2 and wslay, which is very similiar in it's use to node.js. As you might guess a echo server is therefore only about 15 lines of code, but about as performant as your framework. The downsite is that it's not as flexible due to the missing "4-part abtraction" (really… an excellent idea).

That's why your release somehow saddens me: When I'm going to release my framework to the public, it might be pretty good for cross platform apps etc. compared to others, but it will never ever be as popular as yours. Heck… I don't even have 10 twitter followers.

rphillips• 12 years ago

is it open source?

Igglyboo2• 12 years ago

Care to show us what you've got instead of just saying how much better it is than Proxygen?

Also Facebook is a group of people so saying "your" doesn't really sound right.

b3tta2• 12 years ago

I'm sorry… English is not my native tongue. But I'm learning fast. :)

In no way I intended to say that my framework is better overall, but I do think it's better suited for simple things, like apps.

In fact, I think I will integrate something like their "four-part abstraction", because I really think this is a great idea.

amelius2• 12 years ago

Skimming through the article, it seems to me that this server spawns a thread per connection, is that correct?

dcsommer14• 12 years ago

We use a very different model actually. Since spawning OS threads is expensive, we opted for the popular nonblocking-IO approach. Each worker thread (usually 1 per core on the CPU) is given connections in a round robin fashion from the listening socket. The worker thread runs an event loop processing events on the accepted socket.

amelius2• 12 years ago

What kind of programming technique did you use to implement the handling of the protocols? Did you implement them as finite-state machines, or did you use coroutines, or some other technique?

Do you think that C++ is a well suited language for this kind of processing? Is it possible to say, now this project is in a mature state, that other languages (e.g. Rust) could have helped make your implementation simpler?

cbsmith• 12 years ago

Note: as google discovered a few years ago, round-robining the connections is probably less than ideal.

bsaul3• 12 years ago

Looks to me as facebook's answer to golang ?

Building simple, standalone http services with good performances seems to me what those two projects (proxygen and golang) are really about.

Now the question is, how much faster using C++ is, and how much safer and faster writing golang is...

Jare• 12 years ago

I think Facebook is a lot into D, sounds a more appropriate, for lack of a better word, "replacement" for golang.

bsaul3• 12 years ago

I thought so as well, but then why release a c++ lib that's supposedly core to your infra ?

nbm4• 12 years ago

There are some D advocates, users, and enthusiasts (I fall into the last category) at Facebook, and a slowly increasing amount of D code, but the vast majority of infrastructure projects are done in C++, and most people are still choosing it for new projects.

derengel3• 12 years ago

I'm guessing that at facebook scale a GC would be expensive.

bsaul3• 12 years ago

Compared to google scale which can handle it just fine ? :)))

pjmlp3• 12 years ago

Go is a nice language, but so is C++14, specially if you like the expressiveness it provides.

Plus, there are still lots of scenarios where Go tooling still doesn't provide support for. They will eventually, but not if you are starting a project today.

rdrock• 12 years ago

We used to do nginx + gunicorn for our rest services, it was not responding well beyond a point (for a given ec2 instance). We replaced that with nginx + lua (openresty module), we saw almost 10x increase in response times. Would it make sense for us to invest in something like this and hope to see a significant performance gain? Lowering response times is not a big deal but being able to get those same response times on a lower priced instance would definitely help. We have no real C++ skills in the team but we could learn or hire.

72deluxe• 12 years ago

Looks interesting. Does anyone have a comparison of all these plethora of C++ HTTP frameworks, such as Civetweb etc.?

dimman2• 12 years ago

Facebook oughta hire some better scripters, the deps.sh is of terribly low quality. I didn't get more than a couple of lines until i stumble upon this (which tells me the author has no clue :):

'start_dir=`pwd`; trap "cd $start_dir" EXIT;'...

No need to say that the script can be dangerous, in case directory change fails for instance, there's no checks but sudo make uninstall is run anyway in another dir than the intended one.

dcsommer14• 12 years ago

Bash isn't my expertise and I put this together pretty quickly. Please send pull requests! Forgive my ignorance, but what's the danger of the cd'ing in the EXIT trap? Also, I did set -e, so there's no problem of running "sudo make uninstall" from the wrong directory, afaict.

dimman2• 12 years ago

Last msg sounded a bit harsh, sry about that. Anyway, some things to consider:

1. You don't need bash, but rather use /bin/sh to be more compatible with other shells (I don't have bash, neither does a lot of other systems after latest Shellshock incident). There's really no need to limit it to bash (bash is one of many shells but very commonly mistaken for "shell script").

2. The script is executed in a subshell, so the directory your script is in when exiting is irrelevant, it doesn't affect the caller at all. Try by creating a new script that just does 'cd a_dir_that_exists' and run it from a terminal. :)

3. set -e makes the program stop in case of _unhandled_ errors yes, so you're right, the example I gave is indeed wrong and it would stop on the failed cd attempt.

Instead of using '|| true' (to deliberatly ignore errors), the std way to do it is '|| :' (which doesn't fork the true binary). However I would really recommend taking care and handling possible errors.

Proxygen, Facebook's C++ HTTP Framework

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