Memory leak in Go http standard library?

Question

Have a Go binary implement an http server:

package main

import (
    \"net/http\"
)

func main() {
    http.ListenAndServe(\":8080\", nil)
}

I

Answer 1

From the heap pprof you have provided in comments, it looks like you are leaking memory via gorilla/sessions and gorilla/context (almost 400MB).

Refer to this ML thread: https://groups.google.com/forum/#!msg/gorilla-web/clJfCzenuWY/N_Xj9-5Lk6wJ and this GH issue: https://github.com/gorilla/sessions/issues/15

Here is a version that leaks extremely quickly:

package main

import (
    "fmt"
    // "github.com/gorilla/context"
    "github.com/gorilla/sessions"
    "net/http"
)

var (
    cookieStore = sessions.NewCookieStore([]byte("cookie-secret"))
)

func main() {
    http.HandleFunc("/", defaultHandler)
    http.ListenAndServe(":8080", nil)
}

func defaultHandler(w http.ResponseWriter, r *http.Request) {
    cookieStore.Get(r, "leak-test")
    fmt.Fprint(w, "Hi there")
}

Here is one that cleans up and has a relatively static RSS:

package main

import (
    "fmt"
    "github.com/gorilla/context"
    "github.com/gorilla/sessions"
    "net/http"
)

var (
    cookieStore = sessions.NewCookieStore([]byte("cookie-secret"))
)

func main() {
    http.HandleFunc("/", defaultHandler)
    http.ListenAndServe(":8080", context.ClearHandler(http.DefaultServeMux))
}

func defaultHandler(w http.ResponseWriter, r *http.Request) {
    cookieStore.Get(r, "leak-test")
    fmt.Fprint(w, "Hi there")
}