GAE Golang-log.Print（）？

Where can one read logs created by calling function:

log.Print("Message")

The tab "Logs" under Main seems to only display information about what URLs were called, but without any debug information that would be displayed by the application.

As described in the documentation, you should use the Context interface to log instead of log, if you want your logs to show up in the console.

c := appengine.NewContext(r)
c.Infof("Requested URL: %v", r.URL)

The same context object must be passed around in other method calls. Here is an example:

func handleSign(w http.ResponseWriter, r *http.Request) {   
    c := appengine.NewContext(r)
    if err := r.ParseForm(); err != nil {
        writeError(c, err)
        return
    }
}

func writeError(c appengine.Context, err os.Error) {
    c.Errorf("%v", err)
} 

If you are using the new App Engine package google.golang.org/appengine, in the README:

• Logging methods that were on appengine.Context are now functions in google.golang.org/appengine/log

So you should use

c := appengine.NewContext(r)
log.Infof(c, "Requested URL: %v", r.URL)