Go быстрее Rust, Mail.Ru Group сделала замеры

var cluster = require('cluster');
var numCPUs = require('os').cpus().length;
var http = require("http");
var debug = require("debug")("lite");
var workers = [];
var server;

cluster.on('fork', function(worker) {
    workers.push(worker);

    worker.on('online', function() {
        debug("worker %d is online!", worker.process.pid);
    });

    worker.on('exit', function(code, signal) {
        debug("worker %d died", worker.process.pid);
    });

    worker.on('error', function(err) {
        debug("worker %d error: %s", worker.process.pid, err);
    });

    worker.on('disconnect', function() {
        workers.splice(workers.indexOf(worker), 1);
        debug("worker %d disconnected", worker.process.pid);
    });
});

if (cluster.isMaster) {
    debug("Starting pure node.js cluster");

    ['SIGINT', 'SIGTERM'].forEach(function(signal) {
        process.on(signal, function() {
            debug("master got signal %s", signal);
            process.exit(1);
        });
    });

    for (var i = 0; i < numCPUs; i++) {
        cluster.fork();
    }
} else {
    server = http.createServer();

    server.on('listening', function() {
        debug("Listening %o", server._connectionKey);
    });

    var greetingRe = new RegExp("^/greeting/([a-z]+)$", "i");
    server.on('request', function(req, res) {
        var match;

        switch (req.url) {
            case "/": {
                res.statusCode = 200;
                res.statusMessage = 'OK';
                res.write("Hello World!");
                break;
            }

            default: {
                match = greetingRe.exec(req.url);
                res.statusCode = 200;
                res.statusMessage = 'OK';
                res.write("Hello, " + match[1]);    
            }
        }

        res.end();
    });

    server.listen(8080, "127.0.0.1");
}

package main

import (
    "fmt"
    "net/http"
    "regexp"
)

func main() {
    reg := regexp.MustCompile("^/greeting/([a-z]+)$")
    http.ListenAndServe(":8080", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        switch r.URL.Path {
        case "/":
            fmt.Fprint(w, "Hello World!")
        default:
            fmt.Fprintf(w, "Hello, %s", reg.FindStringSubmatch(r.URL.Path)[1])
        }
    }))
}

extern crate hyper;
extern crate regex;

use std::io::Write;
use regex::{Regex, Captures};

use hyper::Server;
use hyper::server::{Request, Response};
use hyper::net::Fresh;
use hyper::uri::RequestUri::{AbsolutePath};

fn handler(req: Request, res: Response<Fresh>) {
    let greeting_re = Regex::new(r"^/greeting/([a-z]+)$").unwrap();

    match req.uri {
        AbsolutePath(ref path) => match (&req.method, &path[..]) {
            (&hyper::Get, "/") => {
                hello(&req, res);
            },
            _ => {
                greet(&req, res, greeting_re.captures(path).unwrap());
            }
        },
        _ => {
            not_found(&req, res);
        }
    };
}

fn hello(_: &Request, res: Response<Fresh>) {
    let mut r = res.start().unwrap();
    r.write_all(b"Hello World!").unwrap();
    r.end().unwrap();
}

fn greet(_: &Request, res: Response<Fresh>, cap: Captures) {
    let mut r = res.start().unwrap();
    r.write_all(format!("Hello, {}", cap.at(1).unwrap()).as_bytes()).unwrap();
    r.end().unwrap();
}

fn not_found(_: &Request, mut res: Response<Fresh>) {
    *res.status_mut() = hyper::NotFound;
    let mut r = res.start().unwrap();
    r.write_all(b"Not Foundn").unwrap();
}

fn main() {
    let _ = Server::http("127.0.0.1:8080").unwrap().handle(handler);
}

package lite

import akka.actor.{ActorSystem, Props}
import akka.io.IO
import spray.can.Http
import akka.pattern.ask
import akka.util.Timeout
import scala.concurrent.duration._
import akka.actor.Actor
import spray.routing._
import spray.http._
import MediaTypes._
import org.json4s.JsonAST._

object Boot extends App {
  implicit val system = ActorSystem("on-spray-can")
  val service = system.actorOf(Props[LiteActor], "demo-service")
  implicit val timeout = Timeout(5.seconds)
  IO(Http) ? Http.Bind(service, interface = "localhost", port = 8080)
}

class LiteActor extends Actor with LiteService {
  def actorRefFactory = context
  def receive = runRoute(route)
}

trait LiteService extends HttpService {
  val route =
    path("greeting" / Segment) { user =>
      get {
        respondWithMediaType(`text/html`) {
          complete("Hello, " + user)
        }
      }
    } ~
    path("") {
      get {
        respondWithMediaType(`text/html`) {
          complete("Hello World!")
        }
      }
    }
}

Дело в том, что в примере Node.js и Go компиляция регулярного выражения происходит единожды, тогда как в Rust компиляция выполняется на каждый запрос. Про Scala ничего сказать не могу.

Выдержка из документации к regex для Rust:

Example: Avoid compiling the same regex in a loop

It is an anti-pattern to compile the same regular expression in a loop since compilation is typically expensive. (It takes anywhere from a few microseconds to a few milliseconds depending on the size of the regex.) Not only is compilation itself expensive, but this also prevents optimizations that reuse allocations internally to the matching engines.

In Rust, it can sometimes be a pain to pass regular expressions around if they're used from inside a helper function. Instead, we recommend using the lazy_static crate to ensure that regular expressions are compiled exactly once.

For example:

#[macro_use] extern crate lazy_static;
extern crate regex;

use regex::Regex;

fn some_helper_function(text: &str) -> bool {
    lazy_static! {
        static ref RE: Regex = Regex::new("...").unwrap();
    }
    RE.is_match(text)
}

fn main() {}

Specifically, in this example, the regex will be compiled when it is used for the first time. On subsequent uses, it will reuse the previous compilation.

Выдержка из документации к regex для Go:

But you should avoid the repeated compilation of a regular expression in a loop for performance reasons.

Как допустили такую ошибку? Я не знаю… Для такого прямолинейного теста это является существенной просадкой в производительности, ведь даже в комментариях автор указал на тормознутость регулярок:

Спасибо! Я тоже думал было переписать на split во всех примерах, но потом показалось, что с regexp будет более жизненно. При оказии попробую прогнать wrk со split.

Упс.

extern crate hyper;
extern crate regex;

#[macro_use] extern crate lazy_static;

use std::io::Write;
use regex::{Regex, Captures};

use hyper::Server;
use hyper::server::{Request, Response};
use hyper::net::Fresh;
use hyper::uri::RequestUri::{AbsolutePath};

fn handler(req: Request, res: Response<Fresh>) {
    lazy_static! {
        static ref GREETING_RE: Regex = Regex::new(r"^/greeting/([a-z]+)$").unwrap();
    }

    match req.uri {
        AbsolutePath(ref path) => match (&req.method, &path[..]) {
            (&hyper::Get, "/") => {
                hello(&req, res);
            },
            _ => {
                greet(&req, res, GREETING_RE.captures(path).unwrap());
            }
        },
        _ => {
            not_found(&req, res);
        }
    };
}

fn hello(_: &Request, res: Response<Fresh>) {
    let mut r = res.start().unwrap();
    r.write_all(b"Hello World!").unwrap();
    r.end().unwrap();
}

fn greet(_: &Request, res: Response<Fresh>, cap: Captures) {
    let mut r = res.start().unwrap();
    r.write_all(format!("Hello, {}", cap.at(1).unwrap()).as_bytes()).unwrap();
    r.end().unwrap();
}

fn not_found(_: &Request, mut res: Response<Fresh>) {
    *res.status_mut() = hyper::NotFound;
    let mut r = res.start().unwrap();
    r.write_all(b"Not Foundn").unwrap();
}

fn main() {
    let _ = Server::http("127.0.0.1:3000").unwrap().handle(handler);
}