limitlistener

This library makes it easy to limit the number of live threads for a given listener. This can be useful in a number of cases to ensure not too many connections will be processed at the same time rather than letting go create new goroutines like there is no tomorrow.

Any call to Accept() when the limit has been reached will wait for any of the currently running connections to close before accepting any new connection.

Usage

l, err := net.Listen("tcp", ":12345")
if err != nil {
    // ...
}

// limit to 128 concurrent processes
l = limitlistener.New(l, 128)

for {
    c, err := l.Accept()
    if err != nil {
        return err
    }

    // safe to start a goroutine here, will be limited to 128 routines
    go handleClient(c)
}

handleClient(c net.Conn) {
    defer c.Close()

    // ...
}

This can be used for a http.Server or anything that takes a net.Listener and will apply the limit as standard as possible. Multiple threads calling Accept() are also supported.

If using this with http.Server be careful to set a ReadTimeout or you may end blocked just with idle connections.