HAProxy is 90k loc while this is 300 loc so they really are different beasts. I would say HAPRoxy is a great general purpose proxy that has most of the features you want while this proxy server is a MVP proxy you can grow off of if you want to do something that HAProxy can't provide.
And yet by "pulling in the JVM" (which is a rounding error in 2017), it's remarkably easy to generate a proxy that actually works as people expect a TCP proxy to work. This doesn't even so much as wait for connections to drain before terminating. This "300-line snippet" (which is reliant on Asio, which is not 300 lines by any stretch) is, as near as I can tell, not viable in real-world conditions and the spirited defenses of it that put it as competitive with real-world, battle-tested solutions are profoundly weird.
(Similarly, because I don't really care about JVM versus not, HAProxy--which I'd probably use for something like this because I have better things to do with my programming time--is 90Kloc because it has stuff to do and does it right. Simple is only better if simple can actually get the job done.)
ASIO does all that. And it compiles to machine code. What you're basically trying to argue is a well-written C++ application will be slower than a well-written java application. That's not going to happen -- at best they will be the same performance.
Netty certainly has a more impressive list of projects using it in real-world high-volume scenarios. That's probably what wins in this case...enough high volume end users such that you've gotten enough edge cases to tweak the software and iron out bugs.
If I had to pick something in the C/C++ space to implement a custom proxy, I would probably stick to something where I could find a similar list of established high volume real world users. Facebook's Proxygen, or some customized HAProxy maybe.
I was trying to say in a nice way that it's unlikely you've created something as fast as netty because a lot of people spent a lot of time optimizing it.
Netty is also a lot easier to extend and more portable
Probably irrelevant to the question of speed, but there is a comment in another thread about hype driven development on HN first page right now where a commenter states they prefer Netty to the alternatives apparently because the alternatives are older or more cumbersome to use, although I may have misread.
Edit: This was a hasty, dumb comment. Please accept my apologies. Netty is not new and I should have known better. For whatever irrational reason, I have a bias against Java and deliberately avoid it. I do know it helps professional programmers get things done easier and faster. I'm an HAproxy user and have probably developed an HAproxy bias.
Netty is hardly the example of a hype driven framework. I'm not sure when it was first released but I've found references from version 2.0 in 2004. It may be older than HAProxy.
Netty is a far more robust, faster, and easier to use framework for TCP proxies than the one the author cooked up and I'm getting downvoted like crazy for saying it.
It's also used internally by Google, Twitter, and netflix. It's embedded in the GRPC library, Cassandra's database driver, Play framework, and Vert.x among many others. Check their related projects page https://netty.io/wiki/related-projects.html
Netty is a phenomenal project, and had the author known about it, I doubt he would have spent the time writing his own TCP proxy.
Netty 2 (the current version that underlies WebSphere and Vertx) was first released in 2004. This stuff is pretty well-bulletproofed. And a lot of folks who know how to write high-performance Java are naturally going to prefer Netty to the C++ alternatives (I am ambivalent; I can do either and I'd probably just use HAProxy to begin with because life is short) because you get competitive performance while ruling out entire classes of errors.
The great thing about battletested, JIT VMs like CLR/JVM/HiPE is that the user code can be compiled once and the providers can keep optimizing them in future versions and also with uptime. As long as memory usage, GC behavior and performance vs. optimized C is close, it's usually a win.
