Raul Martinez Jr juneym

INTRO

Concurrency is a domain I have wanted to explore for a long time because the locks and the race conditions have always intimidated me. I recall somebody suggesting concurrency patterns in golang because they said "you share the data and not the variables".

Amused by that, I searched for "concurrency in golang" and bumped into this awesome slide by Rob Pike: https://talks.golang.org/2012/waza.slide#1 which does a great job of explaining channels, concurrency patterns and a mini-architecture of load-balancer (also explains the above one-liner).

Let's dig in:

Goroutines

Go vs. Scala (Akka) Concurrency

A comparison from 2 weeks using Go.

Actors vs. Functions

Akka's central principle is that there you have an ActorSystem which runs Actors. An Actor is defined as a class and it has a method to receive messages.

Write retrieved emails in a file

As root, install fetchmail

$ apt-get install fetchmail

Check if fetchmail has SSL support: if you see something like "libssl.so.0" then yours has it

$ ldd /usr/bin/fetchmail

	package main

	import (
	"flag"
	"fmt"
	"log"
	"net/http"
	"strconv"
	)

	mgo.SetDebug(true)

	var aLogger *log.Logger
	aLogger = log.New(os.Stderr, "", log.LstdFlags)
	mgo.SetLogger(aLogger)

	#!/bin/bash
	#
	# chkconfig: 2345 55 25
	# description: Openresty
	# processname: nginx
	# config: /usr/local/openresty/nginx/conf/nginx.conf
	# pidfile: /usr/local/openresty/nginx/logs/nginx.pid
	### BEGIN INIT INFO
	# Provides: nginx
	# Required-Start: $local_fs $remote_fs $network $named $syslog $time

	import aiohttp
	import asyncio

	async def get_body(url):
	response = await aiohttp.request('GET', url)
	raw_html = await response.read()
	return raw_html

	async def main():
	# run them sequentially (but the loop can do other stuff in the meanwhile)

	package main

	import (
	"myapp/webserver/app/common"
	"github.com/golang/glog"
	"github.com/gorilla/mux"
	"encoding/json"
	"strconv"
	"flag"
	"fmt"

	"require": {
	[...]
	"besimple/soap": "0.2.*"
	}