My favorite Go multiplexer

When you write a Go webapp, you need to pick web "middleware" and a multiplexer. If you're used to things like Ruby on Rails or Django, they come with their own multiplexer built in. Also known as a router or URL router.
It's basically where you say...

If a request comes in with PATH that matches /some/page/:id then execute the SomePageHandler. And in SomePageHandler you want to get the actual value for that :id part of the PATH.

Anyway, in Go you're spoiled for choices and it took me some time to understand why there are so many and not just one blessed one. The reason for that is that they evolve and often in favor of getting faster and faster.
90% of the time, the I/O is the limiting factor in terms of performance, not the multiplexer, but if you have an endpoint that doesn't depend on much I/O and you're expecting hefty amounts of traffic then why chose a second best?

I first used gorilla/mux because that's what I saw being used in several places. It's very capable and makes it easy to specify which methods should be allowed for specific routes. A good thing about gorilla/mux is that it's compatible with the built-in http.Handler API. That means that can write a handler function that whose signature is w http.ResponseWriter, r *http.Request and if you want to get something out of the path you use vars := mux.Vars(request). For example:

package main

import (
    "fmt"
    "github.com/codegangsta/negroni"
    "github.com/gorilla/mux"
    "net/http"
)

func MyHandler(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)
    fmt.Fprintf(w, "Hello %v\n", vars["id"])
}

func main() {
    mux := mux.NewRouter()
    mux.HandleFunc("/some/page/{id}", MyHandler).Methods("GET")
    n := negroni.Classic()
    n.UseHandler(mux)
    n.Run(":3000")
}

So apparently there's a much faster multiplexer that seems to be popular. It's called httprouter and it's quite pleasant to work with too except that you now have to change your handler to accept a third parameter so it now needs to accept a httprouter.Params parameter too. So, instead the handler(s) need to change. It looks like this:

package main

import (
    "fmt"
    "github.com/codegangsta/negroni"
    "github.com/julienschmidt/httprouter"
    "net/http"
)

func MyHandler(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
    fmt.Fprintf(w, "Hello %v\n", ps.ByName("id"))
}

func main() {
    mux := httprouter.New()
    mux.GET("/some/page/:id", MyHandler)
    n := negroni.Classic()
    n.UseHandler(mux)
    n.Run(":3000")
}

Not too shabby but I can't find out how to do more advanced patterns such as only matching digits e.g. you can do /some/page/{id:[0-9]+} with gorilla/mux.

There's even a benchmark by the author of httprouter that if it doesn't convince you that httprouter is fast, it'll convince you that there are a lot of multiplexers out there to chose from.

And then there's the new kid on the block. My new favorite: bone

It claims to be very fast too. Its README has a comparison between it and gorilla/mux and httprouter.

What attracted me to it is that it's fast and doesn't require the extract ps httprouter.Params on all my handlers. Instead you use val := bone.GetValue(req, "id") within the handler. Here's an example:

package main

import (
    "fmt"
    "github.com/codegangsta/negroni"
    "github.com/go-zoo/bone"
    "net/http"
)

func MyHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello %v\n", bone.GetValue(r, "id"))
}

func main() {
    mux := bone.New()
    mux.Get("/some/page/:id", http.HandlerFunc(MyHandler))
    n := negroni.Classic()
    n.UseHandler(mux)
    n.Run(":3000")
}

Yes, you have to manually wrap every handler function yourself but I don't mind that as much.

Now, for the moment you've all been waiting for, the benchmark.

I take the three sample apps here above and run them with wrk -c 100 -d10 -t10 "http://localhost:3000/some/page/123" at least three times each. The numbers I get are:

# averages across 3 runs each

gorilla/mux   17310.98 requests/sec  +0.7%
httprouter    19216.08 requests/sec  +11.8%
bone          17191.12 requests/sec  0%

I also did a similar benchmark but on a piece of code that doesn't use any parameters from the URL and that runs the server across 8 CPUs instead. The numbers I got from that was:

# averages across 3 runs each

gorilla/mux   43669.26 requests/sec  0%
httprouter    45087.31 requests/sec  +3.2%
bone          47929.04 requests/sec  +9.8%

I think that pretty much concludes that they're all plenty fast. Pick one that you like. I kind like bone myself because I don't need a third parameter on my handlers and the bone.GetValue(r, "id") API feels good.

However, httprouter has much better documentation and feels more mature and newer and fresher than gorilla/mux.