Go routines with Echo

[pacholoamit]

Hello!

Just a quick question. Does Echo have a standard implementation on go routines for concurrency? I.E if a user has called my route, does a go routine spawn for the handler of the route? Or Does Echo take a more default approach of just using 1 main go routine (like when running any go program)? Thanks!

[aldas]

Echo uses standard library http.Server by implementing http.Handler interface (here) and does not spawn any goroutines itself. http.Server creates 1 coroutine per incoming connection and in that coroutine http.Handler interface which is in our case echo.ServeHTTP function is called and middleware->handler chain starts to be executed.

If you are interested how http.Server serves request I recommend looking at these methods

1. http.Server.Serve this is where Server is waiting for incoming connections and creates new coroutine for each connection.
2. http.Server.serve is executing in that new coroutine and is responsible for parsing HTTP requests and calling serverHandler.ServeHTTP before we reach Echo.
3. serverHandler.ServeHTTP does some work on request and calls http.Server.Handler here. This is where Echo code starts to execute as Handler field points to Echo
4. echo.ServeHTTP finds suitable route for Request and creates chain of functions where first are middlewares and last one handler.

As Echo instance implements ServeHTTP we can start serving requests like that

func main() {
	e := echo.New()
	
	// create middlewares and routes here
	
	httpServer := http.Server{
		Addr:    ":80",
		Handler: e, // <-- because Echo implements http.Handler interface
	}
	if err := httpServer.ListenAndServe(); err != http.ErrServerClosed {
		log.Print(fmt.Errorf("error when starting HTTP server: %w", err))
	}
}

[pacholoamit]

Awesome! Thanks for the explanation :)