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Writing high-performance servers in modern C++

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Re: Writing high-performance servers in modern C++

#51

Post by dxhdr »

emcq wrote: post #23
jhartmann wrote: post #5

A lot of people state that Python/PHP/Ruby/Javascript on the dynamic language side and Java and other JVM languages on the statically typed side and much quicker to develop than C++, but being a very experienced Java programmer and a decent Javascript programmer I find that I can program just as fast with C++ as long as you use the right choices of libraries and use C++11 or greater. With libraries like Boost, fbfoll…

It's refreshing to hear other people think the same thing. Most of development time isn't spent physically going code. By picking C you get a high performance layer which can save a lot in infrastructure headaches and has the best performance analysis tools like vtune. That said I've found nodejs slightly nicer for distr

Just curious, how is nodejs nicer for distribution than a binary file?

Re: Writing high-performance servers in modern C++

#52

Post by 72deluxe »

ma2rten wrote: post #9
jhartmann wrote: post #5

A lot of people state that Python/PHP/Ruby/Javascript on the dynamic language side and Java and other JVM languages on the statically typed side and much quicker to develop than C++, but being a very experienced Java programmer and a decent Javascript programmer I find that I can program just as fast with C++ as long as you use the right choices of libraries and use C++11 or greater. With libraries like Boost, fbfoll…

Do you have any pointers to learn modern C++?

Stroustrup's C++ book is good - the tour in the early part of the book covers many aspects quickly but the rest of the book is helpful reference for explaining parts that are only briefly touched on in the first bit (or if you don't quite "get it").

Also, the rest of the book is well written and worth reading for completeness, if not rather lengthy.

Re: Writing high-performance servers in modern C++

#53

Post by 72deluxe »

willtim wrote: post #42
jhartmann wrote: post #5

A lot of people state that Python/PHP/Ruby/Javascript on the dynamic language side and Java and other JVM languages on the statically typed side and much quicker to develop than C++, but being a very experienced Java programmer and a decent Javascript programmer I find that I can program just as fast with C++ as long as you use the right choices of libraries and use C++11 or greater. With libraries like Boost, fbfoll…

Does modern C++ have a decent story for writing nonblocking concurrent code yet? Something that could compete with async-await in C# or monads in functional programming?

Not really familiar with async-await but perhaps std::future and std::promise are helpful?? Less low-level than threads to some extent.

Re: Writing high-performance servers in modern C++

#54

Post by Matthias247 »

Aleman360 wrote: post #47
willtim wrote: post #42

Earlier quoted context omitted.

Does modern C++ have a decent story for writing nonblocking concurrent code yet? Something that could compete with async-await in C# or monads in functional programming?

await is coming, maybe even in C++ 17. Visual Studio already implements it. Way more efficient than the C# implementation too (coroutines) Promises are already there.

Promises are not really there. The C++11 version of std::future is missing future::then, which makes it useless for most concurrent tasks. You can launch subtasks on other threads and wait for the result with this future implementation, but you can't asynchronously wait for results of tasks in the same thread.

This will also only be fixed in C++17. Boost future already implements more of this, but afaik it's still flagged as experimental, so it could change again. And afaik there were also some pending discussions about how futures should interact with schedulers/executors.

Re: Writing high-performance servers in modern C++

#55

Post by aarongolliver »

pcwalton wrote: post #41
matthewaveryusa wrote: post #15

Earlier quoted context omitted.

Perhaps you mean link time? If you're spending a lot of time compiling you are probably suffering from other problems. Most of C++'s issues with compilation come from needing to re-compile entire .cpp files because of a change in a depending .h file. If you properly forward your class declarations instead of including a header in a .h file, don't do template meta meta magic, and think about physical design a bit, you…

A lot of C++ compile time is simply generating and optimizing all the code. Modules don't help with this. Modern C++ style generally requires making a whole bunch of little functions and classes and counting on them to be inlined and SROA'd away. This works remarkably well for runtime, but it exacts a big compilation performance hit simply because you're optimizing so much code.

Interesting anecdote, I was writing a ray tracer recently and instead of using real recursion I tried using a recursive template instead (because who needs i-cache). Basically, every bounce of a ray was a different function with until .

The actual ray-tracing code wasn't that long at all, but if you turned max_max_bounces up (say, 100+) "code-gen" time in visual studio blew up to over one minute. That was the moment when I appreciated what everyone was saying about C++ compile times being quite slow if you (mis)use templates.

Re: Writing high-performance servers in modern C++

#56

Post by markpapadakis »

For what it's worth, the network I/O model design+implementation is rarely what makes the difference between high performance, or not, 'servers' -- and that is a mostly solved problem, at least in terms of patterns and practices that are adopted by 'modern' servers (few threads, no more than actual hardware CPU cores, async.multiplexing, etc).

High performance is about everything else, including processing actual incoming requests efficiently, reducing block/busy time in threads, caring a lot about memory access/caches. They key IMO is concurrency and migrating blocking operations to other dedicated threads, and this is where an efficient coroutines implementation would help both with accomplishing that task, but, perhaps more importantly, keeping the programming model simple.

C++17 will introduce support for reusmable functions ( http://blogs.msdn.com/b/vcblog/archive/2014/11/12/resumable-... ). This will be a game changer. Now, you can approximate this by e.g creating task abstractions and use lower-level(but slow) setjmp/longjmp functions, or just design tasks/functors that hold state that can schedule other tasks in turn, and so on. It works, but the overhead, mental, but also n terms of processing/executing/scheduling can be too great.

Re: Writing high-performance servers in modern C++

#57

Post by acconsta »

willtim wrote: post #42
jhartmann wrote: post #5

A lot of people state that Python/PHP/Ruby/Javascript on the dynamic language side and Java and other JVM languages on the statically typed side and much quicker to develop than C++, but being a very experienced Java programmer and a decent Javascript programmer I find that I can program just as fast with C++ as long as you use the right choices of libraries and use C++11 or greater. With libraries like Boost, fbfoll…

Does modern C++ have a decent story for writing nonblocking concurrent code yet? Something that could compete with async-await in C# or monads in functional programming?

A networking library based on Asio has been proposed for C++17. In the meantime, use Asio.

http://think-async.com/

Re: Writing high-performance servers in modern C++

#58

Post by hnbro »

SeanDav wrote: post #22

I don't understand the point of saying something like: > "I show how to build a modern C++ high-performance, asynchronous echo server that can be written with just 48 lines of code." The fact that it is 48 lines of code is almost meaningless. If the framework was a different design it could be done in 1 line of C++ code or 1 line of COBOL. Given the right library/framework, any application can be done with 1 line of…

it may not be an information-dense sentence, but it is merely a single sentence. one which you've isolated from it's context.

Re: Writing high-performance servers in modern C++

#59

Post by imh »

SeanDav wrote: post #22

I don't understand the point of saying something like: > "I show how to build a modern C++ high-performance, asynchronous echo server that can be written with just 48 lines of code." The fact that it is 48 lines of code is almost meaningless. If the framework was a different design it could be done in 1 line of C++ code or 1 line of COBOL. Given the right library/framework, any application can be done with 1 line of…

48 lines is totally relevant. If I'm coming into the article and thinking, "Oh god, C++? This is going to be a mess," then seeing that it's only 48 lines is a great hook.

Re: Writing high-performance servers in modern C++

#60

Post by SeanDav »

hnbro wrote: post #58
SeanDav wrote: post #22

I don't understand the point of saying something like: > "I show how to build a modern C++ high-performance, asynchronous echo server that can be written with just 48 lines of code." The fact that it is 48 lines of code is almost meaningless. If the framework was a different design it could be done in 1 line of C++ code or 1 line of COBOL. Given the right library/framework, any application can be done with 1 line of…

it may not be an information-dense sentence, but it is merely a single sentence. one which you've isolated from it's context.

It is the direct TL;DR quote from the Author himself, given prominence with blank line separators, italics, bold prefix and located near the very start of the article, so hardly out of context.
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