packets.go:36: unexpected EOF (Invalid Connection)

[rebootcode]

Issue description

Getting Invalid Connection issues.

Error log

[mysql] 2017/09/26 22:38:16 packets.go:36: unexpected EOF
[HTTP Server] http: panic serving xxx.xxx.xxx.xxx:39727: runtime error: invalid memory address or nil pointer dereference
goroutine 25 [running]:
net/http.(*conn).serve.func1(0x1a83a2a0)
        /usr/local/go/src/net/http/server.go:1697 +0x9f
panic(0x84ed320, 0x8849160)
        /usr/local/go/src/runtime/panic.go:491 +0x1d0
database/sql.(*Stmt).Close(0x0, 0x0, 0x0)
        /usr/local/go/src/database/sql/sql.go:2335 +0x2d
main.postLogin.func1(0x88225e0, 0x1a840a00)
        /root/go/src/app/main.go:977 +0x1b8
github.com/kataras/iris/context.Next(0x88225e0, 0x1a840a00)
        /root/go/src/github.com/kataras/iris/context/context.go:851 +0xce
github.com/kataras/iris/context.(*context).Next(0x1a840a00)
        /root/go/src/github.com/kataras/iris/context/context.go:1063 +0x2b
main.main.func2(0x88225e0, 0x1a840a00)
        /root/go/src/app/main.go:57 +0x24f
github.com/kataras/iris/context.Do(0x88225e0, 0x1a840a00, 0x1a827d18, 0x2, 0x2)
        /root/go/src/github.com/kataras/iris/context/context.go:864 +0x61
github.com/kataras/iris/context.(*context).Do(0x1a840a00, 0x1a827d18, 0x2, 0x2)
        /root/go/src/github.com/kataras/iris/context/context.go:1006 +0x43
github.com/kataras/iris/core/router.(*routerHandler).HandleRequest(0x1a8317f0, 0x88225e0, 0x1a840a00)
        /root/go/src/github.com/kataras/iris/core/router/handler.go:216 +0x3f1
github.com/kataras/iris/core/router.(*Router).BuildRouter.func1(0x88198a0, 0x1a578090, 0x1a89a580)
        /root/go/src/github.com/kataras/iris/core/router/router.go:70 +0x6d
github.com/kataras/iris/core/router.(*Router).ServeHTTP(0x1a75bb60, 0x88198a0, 0x1a578090, 0x1a89a580)
        /root/go/src/github.com/kataras/iris/core/router/router.go:147 +0x37
net/http.serverHandler.ServeHTTP(0x1a59f980, 0x88198a0, 0x1a578090, 0x1a89a580)
        /usr/local/go/src/net/http/server.go:2619 +0x8e
net/http.(*conn).serve(0x1a83a2a0, 0x881a0a0, 0x1a8898c0)
        /usr/local/go/src/net/http/server.go:1801 +0x5d1
created by net/http.(*Server).Serve
        /usr/local/go/src/net/http/server.go:2720 +0x1f6
[mysql] 2017/09/26 22:38:16 connection.go:158: invalid connection

Go version: run go version in your console
=> go1.9 linux/386

Server version: E.g. MySQL 5.6, MariaDB 10.0.20
=> 5.5.56-MariaDB

Server OS: E.g. Debian 8.1 (Jessie), Windows 10
=> Centos

[rebootcode]

The way to solve is :-
db.SetMaxIdleConns(0)

[heisGarvit]

There is a typo in your solution maybe version difference...

https://golang.org/pkg/database/sql/#DB.SetMaxIdleConns

so I used db.SetMaxIdleConns(0) and program ran. Thanks for the solution!

[rebootcode]

@heisGarvit - fixed

[notr1ch]

Also running into this, seems strange that the generally accepted solution everywhere is to "disable idle connections". Was the root cause for this discovered? Are there plans to fix it so that idle connections work as intended?

[methane]

Also running into this, seems strange that the generally accepted solution everywhere is to "disable idle connections".

General solution is DB.SetConnMaxLifetime(time.Second).

Was the root cause for this discovered? Are there plans to fix it so that idle connections work as intended?

Root cause is TCP and request-response protocol. HTTP keep-alive has same problem.
Client should have shorter timeout than server. Otherwise, client may try to use dead connection.
And if the request may not be idempotent, client can't retry automatically.

For example, AWS's ELB (load balancer, which is "client" to application) has 60sec keep-alive.
And it recommends 120sec keep-alive timeout on application server side.
https://aws.amazon.com/jp/premiumsupport/knowledge-center/apache-backend-elb/

[methane]

Even if server's wait_timeout is long enough, router or OS may close long idle connection
to reduce resource usage. Which cause this error too.
So I recommend 1sec ~ 10sec timeout, unless you're network expert and you know optimal
timeout length.

[muxalko]

Hi,
Recently encountered the same issue, and found this topic useful.
Hope it helps,

[mikegleasonjr]

Another way to solve this is to set the tcp keep alive on the connection:

func init() {
	mysql.RegisterDial("tcp", func(addr string) (net.Conn, error) {
		conn, err := net.Dial("tcp", addr)
		if err != nil {
			return nil, err
		}

		type keepAliveSetter interface {
			SetKeepAlive(keepalive bool) error
			SetKeepAlivePeriod(d time.Duration) error
		}

		if setter, ok := conn.(keepAliveSetter); ok {
			if err := setter.SetKeepAlive(true); err != nil {
			} else if err := setter.SetKeepAlivePeriod(time.Minute); err != nil {
			}
		}

		return conn, nil
	})
}

[methane]

TCP Keep-Alive solves only very limited cause of this issue.
It's not recommended way. SetConnMaxLifetime() is recommended.