Fast HTTP package for Go. Tuned for high performance. Zero memory allocations in hot paths. Up to 10x faster than net/http
Fast HTTP package for Go. Tuned for high performance. Zero memory allocations in hot paths. Up to 10x faster than net/http
Fast HTTP implementation for Go.
fasthttp was designed for some high performance edge cases. Unless your server/client needs to handle thousands of small to medium requests per second and needs a consistent low millisecond response time fasthttp might not be for you. For most cases net/http is much better as it's easier to use and can handle more cases. For most cases you won't even notice the performance difference.
Currently fasthttp is successfully used by VertaMedia in a production serving up to 200K rps from more than 1.5M concurrent keep-alive connections per physical server.
TechEmpower Benchmark round 23 results
Switching from net/http to fasthttp
In short, fasthttp server is up to 6 times faster than net/http. Below are benchmark results.
GOMAXPROCS=1
net/http server:
…
fasthttp server:
…
GOMAXPROCS=4
net/http server:
…
fasthttp server:
…
In short, fasthttp client is up to 4 times faster than net/http. Below are benchmark results.
GOMAXPROCS=1
net/http client:
…
fasthttp client:
…
GOMAXPROCS=4
net/http client:
…
fasthttp client:
…
go get -u github.com/valyala/fasthttp
Unfortunately, fasthttp doesn't provide API identical to net/http. See the FAQ for details. There is net/http -> fasthttp handler converter, but it is better to write fasthttp request handlers by hand in order to use all of the fasthttp advantages (especially high performance :) ).
Important points:
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The RequestHandler accepts only one argument - RequestCtx. It contains all the functionality required for http request processing and response writing. Below is an example of a simple request handler conversion from net/http to fasthttp.
// net/http request handler
requestHandler := func(w http.ResponseWriter, r *http.Request) {
switch r.URL.Path {
case "/foo":
fooHandler(w, r)
case "/bar":
barHandler(w, r)
default:
http.Error(w, "Unsupported path", http.StatusNotFound)
}
}
// the corresponding fasthttp request handler
requestHandler := func(ctx *fasthttp.RequestCtx) {
switch string(ctx.Path()) {
case "/foo":
fooHandler(ctx)
case "/bar":
barHandler(ctx)
default:
ctx.Error("Unsupported path", fasthttp.StatusNotFound)
}
}
Fasthttp allows setting response headers and writing response body in an arbitrary order. There is no 'headers first, then body' restriction like in net/http. The following code is valid for fasthttp:
…
Fasthttp doesn't provide ServeMux, but there are more powerful third-party routers and web frameworks with fasthttp support:
Net/http code with simple ServeMux is trivially converted to fasthttp code:
// net/http code
m := &http.ServeMux{}
m.HandleFunc("/foo", fooHandlerFunc)
m.HandleFunc("/bar", barHandlerFunc)
m.Handle("/baz", bazHandler)
http.ListenAndServe(":80", m)
// the corresponding fasthttp code
m := func(ctx *fasthttp.RequestCtx) {
switch string(ctx.Path()) {
case "/foo":
fooHandlerFunc(ctx)
case "/bar":
barHandlerFunc(ctx)
case "/baz":
bazHandler.HandlerFunc(ctx)
default:
ctx.Error("not found", fasthttp.StatusNotFound)
}
}
fasthttp.ListenAndServe(":80", m)
Because creating a new channel for every request is just too expensive, so the channel returned by RequestCtx.Done() is only closed when the server is shutting down.
func main() {
fasthttp.ListenAndServe(":8080", fasthttp.TimeoutHandler(func(ctx *fasthttp.RequestCtx) {
select {
case <-ctx.Done():
// ctx.Done() is only closed when the server is shutting down.
log.Println("context cancelled")
return
case <-time.After(10 * time.Second):
log.Println("process finished ok")
}
}, time.Second*2, "timeout"))
}
net/http -> fasthttp conversion table:
var (
w http.ResponseWriter
r *http.Request
ctx *fasthttp.RequestCtx
)
VERY IMPORTANT! Fasthttp disallows holding references to RequestCtx or to its' members after returning from RequestHandler. Otherwise data races are inevitable. Carefully inspect all the net/http request handlers converted to fasthttp whether they retain references to RequestCtx or to its' members after returning. RequestCtx provides the following band aids for this case: